Configurazione di Frida su iOS

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Installazione di Frida

Passaggi per installare Frida su un dispositivo Jailbroken:

1. Apri l’app Cydia/Sileo.
2. Vai su Manage -> Sources -> Edit -> Add.
3. Inserisci “https://build.frida.re” come URL.
4. Vai alla sorgente Frida appena aggiunta.
5. Installa il pacchetto Frida.

Se stai usando Corellium dovrai scaricare la release di Frida da https://github.com/frida/frida/releases (frida-gadget-[yourversion]-ios-universal.dylib.gz) e decomprimere e copiare nella posizione dylib richiesta da Frida, e.g.: /Users/[youruser]/.cache/frida/gadget-ios.dylib

Dopo l’installazione, puoi usare dal tuo PC il comando frida-ls-devices e verificare che il dispositivo appaia (il tuo PC deve poterci accedere).
Esegui anche frida-ps -Uia per controllare i processi in esecuzione sul telefono.

Frida senza dispositivo Jailbroken & senza patchare l’app

Consulta questo post del blog su come usare Frida su dispositivi non-jailbroken senza patchare l’app: https://mrbypass.medium.com/unlocking-potential-exploring-frida-objection-on-non-jailbroken-devices-without-application-ed0367a84f07

Installazione del client Frida

Installa frida tools:

pip install frida-tools
pip install frida

Con il Frida server installato e il device acceso e connesso, controlla se il client funziona:

frida-ls-devices  # List devices
frida-ps -Uia     # Get running processes

Frida Trace

Note

Se in qualsiasi momento hai bisogno di formazione su reversing iOS / Frida, consulta https://reversing.training/

# Functions
## Trace all functions with the word "log" in their name
frida-trace -U <program> -i "*log*"
frida-trace -U <program> -i "*log*" | swift demangle # Demangle names

# Objective-C
## Trace all methods of all classes
frida-trace -U <program> -m "*[* *]"

## Trace all methods with the word "authentication" from classes that start with "NE"
frida-trace -U <program> -m "*[NE* *authentication*]"

# Plug-In
## To hook a plugin that is momentarely executed prepare Frida indicating the ID of the Plugin binary
frida-trace -U -W <if-plugin-bin> -m '*[* *]'

Ottieni tutte le classi e i metodi

• Completamento automatico: Esegui semplicemente frida -U <program>

• Ottieni tutte le classi disponibili (filtra per stringa)

// frida -U <program> -l /tmp/script.js

var filterClass = "" // Leave empty to list all classes, or set to "NSString" for example

if (ObjC.available) {
var classCount = 0
var classList = []

for (var className in ObjC.classes) {
if (ObjC.classes.hasOwnProperty(className)) {
if (!filterClass || className.toLowerCase().includes(filterClass.toLowerCase())) {
classList.push(className)
classCount++
}
}
}

// Sort alphabetically for better readability
classList.sort()

console.log(`\n[*] Found ${classCount} classes matching '${filterClass || "all"}':\n`)
classList.forEach(function(name) {
console.log(name)
})
} else {
console.log("[!] Objective-C runtime is not available.")
}

• Ottieni tutti i metodi di una classe (filtra per stringa)

// frida -U <program> -l /tmp/script.js

var specificClass = "NSURL" // Change to your target class
var filterMethod = "" // Leave empty to list all methods, or set to "init" for example

if (ObjC.available) {
if (ObjC.classes.hasOwnProperty(specificClass)) {
var methods = ObjC.classes[specificClass].$ownMethods
var filteredMethods = []

for (var i = 0; i < methods.length; i++) {
if (!filterMethod || methods[i].toLowerCase().includes(filterMethod.toLowerCase())) {
filteredMethods.push(methods[i])
}
}

console.log(`\n[*] Found ${filteredMethods.length} methods in class '${specificClass}' matching '${filterMethod || "all"}':\n`)
filteredMethods.forEach(function(method) {
console.log(`${specificClass}: ${method}`)
})

// Also show inherited methods
var inheritedMethods = ObjC.classes[specificClass].$methods
console.log(`\n[*] Total methods including inherited: ${inheritedMethods.length}`)
} else {
console.log(`[!] Class '${specificClass}' not found.`)
console.log("[*] Tip: Use the class enumeration script to find available classes.")
}
} else {
console.log("[!] Objective-C runtime is not available.")
}

• Chiamare una funzione

// Find the address of the function to call
const func_addr = Module.findExportByName("<Prog Name>", "<Func Name>")

if (!func_addr) {
console.log("[!] Function not found. Available exports:")
Module.enumerateExports("<Prog Name>").slice(0, 10).forEach(function(exp) {
console.log(`  ${exp.name} at ${exp.address}`)
})
throw new Error("Function not found")
}

// Declare the function to call
const func = new NativeFunction(
func_addr,
"void",
["pointer", "pointer", "pointer"],
{}
)

var arg0 = null
var attempt = 0
var maxAttempts = 100

console.log("[*] Waiting for function to be called to capture arg0...")

// In this case to call this function we need to intercept a call to it to copy arg0
Interceptor.attach(func_addr, {
onEnter: function (args) {
if (!arg0) {
arg0 = new NativePointer(args[0])
console.log(`[+] Captured arg0: ${arg0}`)
}
},
})

// Wait until a call to the func occurs (with timeout)
while (!arg0 && attempt < maxAttempts) {
Thread.sleep(0.1)
attempt++
if (attempt % 10 == 0) {
console.log(`[*] Still waiting... (${attempt}/${maxAttempts})`)
}
}

if (!arg0) {
throw new Error("Timeout: Could not capture arg0. Try triggering the function in the app.")
}

// Now call the function with custom arguments
var arg1 = Memory.allocUtf8String("custom_tag")
var arg2 = Memory.allocUtf8String("Custom message from Frida")

console.log("[+] Calling function with custom arguments...")
func(arg0, arg1, arg2)

console.log("[+] Function called successfully!")

Hook Objective-C Methods

Intercetta e modifica le chiamate ai metodi Objective-C:

// frida -U <program> -l /tmp/hook-objc.js

// Hook a specific Objective-C method
function hookMethod(className, methodName) {
var hook = ObjC.classes[className][methodName]

if (!hook) {
console.log(`[!] Method ${className}.${methodName} not found`)
return
}

Interceptor.attach(hook.implementation, {
onEnter: function(args) {
console.log(`\n[*] Called: [${className} ${methodName}]`)

// args[0] is self, args[1] is _cmd (selector)
// Actual method arguments start at args[2]

// Print self
try {
var selfObj = new ObjC.Object(args[0])
console.log(`    self: ${selfObj}`)
} catch (e) {
console.log(`    self: ${args[0]}`)
}

// Print arguments (adjust based on method signature)
for (var i = 2; i < 6; i++) {
if (args[i]) {
try {
// Try as ObjC object
var obj = new ObjC.Object(args[i])
console.log(`    arg[${i-2}]: ${obj} (${obj.$className})`)
} catch (e) {
// Try as string
try {
var str = args[i].readUtf8String()
console.log(`    arg[${i-2}]: "${str}"`)
} catch (e2) {
// Just print pointer
console.log(`    arg[${i-2}]: ${args[i]}`)
}
}
}
}

// You can modify arguments here
// args[2] = ObjC.classes.NSString.stringWithString_("Modified!")
},
onLeave: function(retval) {
// Print return value
try {
var ret = new ObjC.Object(retval)
console.log(`    => ${ret}`)
} catch (e) {
console.log(`    => ${retval}`)
}

// You can modify return value here
// retval.replace(ObjC.classes.NSString.stringWithString_("Hijacked!"))
}
})

console.log(`[+] Hooked: [${className} ${methodName}]`)
}

// Example: Hook multiple methods
if (ObjC.available) {
console.log("[*] Objective-C runtime available")

// Hook authentication methods
hookMethod("LoginViewController", "- authenticate:")
hookMethod("AuthManager", "- validatePassword:")

// Hook data storage methods
hookMethod("NSUserDefaults", "+ standardUserDefaults")
hookMethod("NSUserDefaults", "- setObject:forKey:")
hookMethod("NSUserDefaults", "- objectForKey:")

// Hook crypto methods
hookMethod("NSString", "- dataUsingEncoding:")

// Hook network methods
hookMethod("NSURLSession", "- dataTaskWithRequest:completionHandler:")

console.log("[+] All hooks installed successfully")
} else {
console.log("[!] Objective-C runtime not available")
}

Hooking avanzato in Objective-C con method swizzling:

// Replace method implementation entirely
function swizzleMethod(className, methodName, newImplementation) {
if (!ObjC.available) {
console.log("[!] Objective-C runtime not available")
return
}

var targetClass = ObjC.classes[className]
if (!targetClass) {
console.log(`[!] Class ${className} not found`)
return
}

var method = targetClass[methodName]
if (!method) {
console.log(`[!] Method ${methodName} not found in ${className}`)
return
}

var originalImpl = method.implementation

method.implementation = ObjC.implement(method, function(handle, selector) {
// handle is 'self', selector is the method selector
console.log(`[*] Swizzled method called: [${className} ${methodName}]`)

// Call custom logic
var result = newImplementation(handle, selector, arguments)

// Optionally call original
// var original = new NativeFunction(originalImpl, method.returnType, method.argumentTypes)
// return original(handle, selector, ...)

return result
})

console.log(`[+] Swizzled: [${className} ${methodName}]`)
}

// Example: Always return true for authentication
swizzleMethod("AuthManager", "- isAuthenticated", function(self, sel) {
console.log("[!] Bypassing authentication check!")
return 1 // true
})

// Example: Bypass jailbreak detection
if (ObjC.available) {
var jailbreakMethods = [
["JailbreakDetector", "- isJailbroken"],
["SecurityChecker", "- checkJailbreak"],
["AntiDebug", "- isDebugged"]
]

jailbreakMethods.forEach(function(item) {
try {
swizzleMethod(item[0], item[1], function() {
console.log(`[!] Bypassing ${item[0]}.${item[1]}`)
return 0 // false
})
} catch (e) {
// Method doesn't exist, ignore
}
})
}

Frida Fuzzing

Frida Stalker

From the docs: Stalker è il motore di tracciamento del codice di Frida. Permette di seguire i thread, catturando ogni funzione, ogni blocco, perfino ogni istruzione che viene eseguita.

Hai un esempio che implementa Frida Stalker in https://github.com/poxyran/misc/blob/master/frida-stalker-example.py

Questo è un altro esempio per avviare Frida Stalker ogni volta che viene chiamata una funzione:

console.log("[*] Starting Stalker setup...")

const TARGET_MODULE = "<Program>"
const TARGET_FUNCTION = "<function_name>"

const func_addr = Module.findExportByName(TARGET_MODULE, TARGET_FUNCTION)

if (!func_addr) {
console.log(`[!] Function '${TARGET_FUNCTION}' not found in module '${TARGET_MODULE}'`)
throw new Error("Target function not found")
}

console.log(`[+] Found target function at: ${func_addr}`)

const func = new NativeFunction(
func_addr,
"void",
["pointer", "pointer", "pointer"],
{}
)

var callCount = 0
var coverageMap = {}

Interceptor.attach(func_addr, {
onEnter: function (args) {
callCount++
console.log(`\n[*] Call #${callCount} - Message: ${args[2].readCString()}`)

// Follow the current thread
Stalker.follow(Process.getCurrentThreadId(), {
events: {
compile: true, // Only collect coverage for newly encountered blocks
},
onReceive: function (events) {
const bbs = Stalker.parse(events, {
stringify: false,
annotate: false,
})

// Track unique code blocks for coverage
var newBlocks = 0
bbs.flat().forEach(function(addr) {
var addrStr = addr.toString()
if (!coverageMap[addrStr]) {
coverageMap[addrStr] = true
newBlocks++
}
})

console.log(`[+] Executed ${bbs.flat().length} blocks (${newBlocks} new)`)
console.log(`[+] Total unique blocks covered: ${Object.keys(coverageMap).length}`)

// Optionally print trace (can be verbose)
if (callCount <= 3) { // Only print first 3 traces
console.log("\n[*] Execution trace:")
bbs.flat().slice(0, 20).forEach(function(addr) { // Limit to first 20
console.log(`  ${DebugSymbol.fromAddress(addr)}`)
})
if (bbs.flat().length > 20) {
console.log(`  ... and ${bbs.flat().length - 20} more blocks`)
}
}
},
})
},
onLeave: function (retval) {
Stalker.unfollow(Process.getCurrentThreadId())
Stalker.flush() // Important: flush all events before unfollow
Stalker.garbageCollect() // Clean up
},
})

console.log("[+] Stalker attached successfully. Waiting for function calls...")

Caution

Questo è interessante per il debugging ma per il fuzzing, essere costantemente .follow() e .unfollow() è molto inefficiente.

Fpicker

fpicker è una suite di fuzzing basata su Frida che offre diverse modalità per il fuzzing in-process, come una modalità AFL++ o una modalità di tracing passivo. Dovrebbe funzionare su tutte le piattaforme supportate da Frida.

• Install fpicker & radamsa

# Get fpicker
git clone https://github.com/ttdennis/fpicker
cd fpicker

# Get Frida core devkit and prepare fpicker
wget https://github.com/frida/frida/releases/download/16.1.4/frida-core-devkit-16.1.4-[yourOS]-[yourarchitecture].tar.xz
# e.g. https://github.com/frida/frida/releases/download/16.1.4/frida-core-devkit-16.1.4-macos-arm64.tar.xz
tar -xf ./*tar.xz
cp libfrida-core.a libfrida-core-[yourOS].a #libfrida-core-macos.a

# Install fpicker
make fpicker-[yourOS] # fpicker-macos
# This generates ./fpicker

# Install radamsa (fuzzer generator)
brew install radamsa

• Preparare il FS:

# From inside fpicker clone
mkdir -p examples/target-app # Where the fuzzing script will be
mkdir -p examples/target-app/out # For code coverage and crashes
mkdir -p examples/target-app/in # For starting inputs

# Create at least 1 input for the fuzzer
echo Hello World > examples/target-app/in/0

• Fuzzer script (examples/target-app/myfuzzer.js):

// Import the fuzzer base class
import { Fuzzer } from "../../harness/fuzzer.js"

class TargetAppFuzzer extends Fuzzer {
constructor() {
console.log("[*] TargetAppFuzzer: Initializing fuzzer...")

// ============================================================
// CONFIGURATION SECTION
// ============================================================
// These are the values you need to customize for your target:

const TARGET_MODULE = "<Program name>"      // The binary/library name (e.g., "MyApp" or "libcrypto.dylib")
// Use Process.enumerateModules() to find module names

const TARGET_FUNCTION = "<func name to fuzz>" // The exported function name to fuzz (e.g., "process_input")
// Use Module.enumerateExports() to find function names

const CAPTURE_TIMEOUT = 30                   // Seconds to wait for capturing function arguments
// Increase if function is rarely called

// ============================================================
// FUNCTION DISCOVERY
// ============================================================
// Find the address of the target function in memory
console.log(`[*] Looking for function '${TARGET_FUNCTION}' in module '${TARGET_MODULE}'...`)
var target_addr = Module.findExportByName(TARGET_MODULE, TARGET_FUNCTION)

// Validate that the function was found
if (!target_addr) {
console.log(`[!] Function not found. Available exports from ${TARGET_MODULE}:`)
Module.enumerateExports(TARGET_MODULE).slice(0, 10).forEach(function(exp) {
console.log(`  - ${exp.name}`)
})
throw new Error(`Function '${TARGET_FUNCTION}' not found`)
}

console.log(`[+] Found target function at: ${target_addr}`)

// ============================================================
// FUNCTION SIGNATURE SETUP
// ============================================================
// Create a NativeFunction wrapper so we can call the function
// Signature: void function_name(pointer arg0, pointer arg1, pointer arg2)
// IMPORTANT: Adjust the return type and argument types to match your target function
//   - First parameter: return type ("void", "int", "pointer", etc.)
//   - Second parameter: array of argument types
var target_func = new NativeFunction(
target_addr,
"void",                              // Return type - change if function returns a value
["pointer", "pointer", "pointer"],   // Argument types - adjust based on actual function signature
{}
)

// ============================================================
// PARENT CLASS INITIALIZATION
// ============================================================
// Initialize the fpicker Fuzzer base class with our target information
super(TARGET_MODULE, target_addr, target_func)
this.target_addr = target_addr

// ============================================================
// STATISTICS TRACKING
// ============================================================
// Keep track of fuzzing progress and results
this.fuzzCount = 0      // Total number of fuzzing iterations executed
this.crashCount = 0     // Number of crashes/exceptions encountered
this.startTime = Date.now()  // Start time for calculating execution rate

// ============================================================
// STATIC ARGUMENTS PREPARATION
// ============================================================
// Some functions require specific arguments that don't change
// Here we prepare the second argument (a tag string)
this.tag = Memory.allocUtf8String("FUZZ_TAG")
console.log("[+] Allocated tag argument")

// ============================================================
// DYNAMIC ARGUMENT CAPTURE
// ============================================================
// Many functions require a context pointer or handle as first argument
// We can't create this ourselves, so we intercept a real call to capture it

var captured_ptr = null   // Will hold the captured pointer
var attempts = 0          // Counter for timeout mechanism
var maxAttempts = CAPTURE_TIMEOUT * 10 // Total attempts (checking every 100ms)

console.log(`[*] Waiting up to ${CAPTURE_TIMEOUT}s to capture first argument...`)
console.log("[*] Please trigger the target function in the app!")
console.log("[*] (Interact with the app to make it call the function)")

// Attach an interceptor to capture arguments when function is called
var interceptor = Interceptor.attach(this.target_addr, {
onEnter: function (args) {
// Only capture once (first call)
if (!captured_ptr) {
captured_ptr = new NativePointer(args[0])
console.log(`[+] Captured first argument: ${captured_ptr}`)

// Try to read and display other arguments for debugging
// This helps verify we're hooking the right function
try {
if (args[1]) console.log(`[*] Arg 1: ${args[1].readCString()}`)
if (args[2]) console.log(`[*] Arg 2: ${args[2].readCString()}`)
} catch (e) {
console.log("[*] Could not read string arguments (might not be strings)")
}
}
},
})

// ============================================================
// WAIT FOR CAPTURE WITH TIMEOUT
// ============================================================
// Poll until we capture the argument or timeout
while (!captured_ptr && attempts < maxAttempts) {
Thread.sleep(0.1)  // Sleep 100ms between checks
attempts++

// Print progress every 5 seconds so user knows we're still waiting
if (attempts % 50 == 0) {
console.log(`[*] Still waiting... (${attempts / 10}s / ${CAPTURE_TIMEOUT}s)`)
}
}

// ============================================================
// CLEANUP AND VALIDATION
// ============================================================
// Detach the interceptor - we don't need it anymore
interceptor.detach()

// Check if we successfully captured the argument
if (!captured_ptr) {
throw new Error(`Timeout: Could not capture first argument after ${CAPTURE_TIMEOUT}s. Ensure the function is being called.`)
}

// Store the captured pointer for use in fuzz() method
this.captured_ptr = captured_ptr
console.log("[+] Fuzzer initialization complete!")
console.log("[+] Ready to fuzz...")
}

// This function is called by fpicker for each fuzzing iteration
// @param payload: NativePointer - Pointer to the fuzzing input data in memory
// @param len: Number - Length of the input data in bytes
fuzz(payload, len) {
this.fuzzCount++

try {
// ============================================================
// STEP 1: Convert the raw payload to a usable format
// ============================================================
// The payload comes as a pointer to memory. We need to:
// 1. Read the raw bytes from that memory location
// 2. Allocate new memory for a null-terminated C string
// 3. Copy the data and add null terminator

var payload_mem = Memory.alloc(len + 1)  // Allocate len + 1 for null terminator
Memory.copy(payload_mem, payload, len)   // Copy the payload bytes
payload_mem.add(len).writeU8(0)          // Write null terminator at the end

// ============================================================
// STEP 2: Progress monitoring and statistics
// ============================================================
// Log progress every 100 iterations to avoid spamming console
if (this.fuzzCount % 100 == 0) {
var elapsed = ((Date.now() - this.startTime) / 1000).toFixed(2)
var rate = (this.fuzzCount / elapsed).toFixed(2)
console.log(`[*] Fuzzing iteration ${this.fuzzCount} (${rate} exec/s, ${this.crashCount} crashes)`)
}

// ============================================================
// STEP 3: Debug logging for initial iterations
// ============================================================
// For the first 3 payloads, show what we're testing
// This helps verify the fuzzer is working correctly
if (this.fuzzCount <= 3) {
try {
var preview = payload.readCString(Math.min(len, 50))
console.log(`[*] Payload preview (${len} bytes): ${preview}${len > 50 ? '...' : ''}`)
} catch (e) {
// If readCString fails, it's likely binary data
console.log(`[*] Binary payload (${len} bytes)`)
}
}

// ============================================================
// STEP 4: Execute the target function with the fuzzed input
// ============================================================
// Call the target function with:
// - captured_ptr: The first argument we captured during initialization
// - tag: A static tag/label for the log entry
// - payload_mem: Our fuzzed input as a null-terminated string
this.target_function(this.captured_ptr, this.tag, payload_mem)

} catch (e) {
// ============================================================
// STEP 5: Exception handling
// ============================================================
// If the target function crashes or throws an exception:
// 1. Increment crash counter
// 2. Log the details for later analysis
// 3. Re-throw so fpicker can record it
this.crashCount++
console.log(`[!] Exception in iteration ${this.fuzzCount}: ${e.message}`)
console.log(`[!] Stack: ${e.stack}`)

// Re-throw to let fpicker handle crash detection and logging
throw e
}
}

// Optional: Cleanup method called when fuzzing ends
cleanup() {
var elapsed = ((Date.now() - this.startTime) / 1000).toFixed(2)
console.log(`\n[*] Fuzzing session complete:`)
console.log(`    - Total iterations: ${this.fuzzCount}`)
console.log(`    - Total crashes: ${this.crashCount}`)
console.log(`    - Duration: ${elapsed}s`)
console.log(`    - Average rate: ${(this.fuzzCount / elapsed).toFixed(2)} exec/s`)
}
}

console.log("[*] Creating fuzzer instance...")
const f = new TargetAppFuzzer()
rpc.exports.fuzzer = f

// Export cleanup method if available
if (f.cleanup) {
rpc.exports.cleanup = f.cleanup.bind(f)
}

• Compilare il fuzzer:

# From inside fpicker clone
## Compile from "myfuzzer.js" to "harness.js"
frida-compile examples/target-app/myfuzzer.js -o harness.js

• Esegui il fuzzer fpicker usando radamsa:

# Basic fuzzing with radamsa mutation
fpicker -v --fuzzer-mode active -e attach -p <Program to fuzz> -D usb \
-o examples/target-app/out/ -i examples/target-app/in/ -f harness.js \
--standalone-mutator cmd --mutator-command "radamsa"

# With AFL++ mode for better coverage
fpicker -v --fuzzer-mode afl -e attach -p <Program to fuzz> -D usb \
-o examples/target-app/out/ -i examples/target-app/in/ -f harness.js

# You can find code coverage and crashes in examples/target-app/out/
# Check crashes: ls -la examples/target-app/out/crashes/
# Check coverage: ls -la examples/target-app/out/coverage/

Caution

In questo caso non stiamo riavviando l’app o ripristinando lo stato dopo ogni payload. Quindi, se Frida rileva un crash i successivi input dopo quel payload potrebbero anche causare un crash all’app (perché l’app è in uno stato instabile) anche se l’input non dovrebbe causare un crash all’app.

Inoltre, Frida si aggancerà ai segnali di eccezione di iOS, quindi quando Frida rileva un crash, probabilmente non verranno generati iOS crash reports.

Per evitarlo, per esempio, potremmo riavviare l’app dopo ogni crash rilevato da Frida.

Fuzzing avanzato con monitoraggio dei crash

Per un fuzzing più robusto con rilevamento automatico dei crash e riavvio dell’app, usa questo script avanzato:

import { Fuzzer } from "../../harness/fuzzer.js"

class AdvancedFuzzer extends Fuzzer {
constructor() {
console.log("[*] Advanced Fuzzer: Initializing with crash monitoring...")

// ============================================================
// CONFIGURATION
// ============================================================
const TARGET_MODULE = "<Program name>"   // Module containing the target function
const TARGET_FUNCTION = "<func name>"    // Function to fuzz

// ============================================================
// FIND AND SETUP TARGET FUNCTION
// ============================================================
var target_addr = Module.findExportByName(TARGET_MODULE, TARGET_FUNCTION)
if (!target_addr) {
throw new Error(`Function '${TARGET_FUNCTION}' not found`)
}

var target_func = new NativeFunction(target_addr, "void", ["pointer", "pointer", "pointer"], {})
super(TARGET_MODULE, target_addr, target_func)

// ============================================================
// ADVANCED CRASH DETECTION SETUP
// ============================================================
// Install comprehensive crash monitoring before starting fuzzing
this.setupCrashMonitoring()

// Hook dangerous functions that often indicate crashes
this.setupSignalHandlers()

// ============================================================
// CAPTURE RUNTIME ARGUMENTS
// ============================================================
// Capture the context pointer needed to call the function
this.captured_ptr = this.captureArgument(target_addr, 0)
this.tag = Memory.allocUtf8String("FUZZ")

console.log("[+] Advanced fuzzer ready with crash monitoring enabled")
}

// ============================================================
// CRASH MONITORING SETUP
// ============================================================
// This method installs a global exception handler that catches:
// - Segmentation faults (invalid memory access)
// - Arithmetic exceptions (divide by zero, etc.)
// - Abort signals
// - Any other exceptions that would normally crash the app
setupCrashMonitoring() {
Process.setExceptionHandler(function(details) {
console.log("\n[!!!] CRASH DETECTED [!!!]")
console.log(`[!] Type: ${details.type}`)           // Exception type (e.g., "access-violation")
console.log(`[!] Address: ${details.address}`)     // Address where crash occurred

// If it's a memory-related crash, show the operation and address
console.log(`[!] Memory operation: ${details.memory ? details.memory.operation : 'N/A'}`)

// ============================================================
// DUMP CPU REGISTERS
// ============================================================
// Show CPU register state at crash time (useful for exploitation analysis)
if (details.context) {
console.log("[!] Registers:")
Object.keys(details.context).slice(0, 8).forEach(function(reg) {
console.log(`    ${reg}: ${details.context[reg]}`)
})
}

// ============================================================
// DUMP CALL STACK (BACKTRACE)
// ============================================================
// Show the call stack leading to the crash
// This helps identify which code path triggered the issue
console.log("[!] Backtrace:")
Thread.backtrace(details.context, Backtracer.ACCURATE)
.map(DebugSymbol.fromAddress)
.slice(0, 10)
.forEach(function(symbol, idx) {
console.log(`    ${idx}: ${symbol}`)
})

// Return false to let iOS handle the crash (generates crash report)
// Return true to suppress the crash and continue (dangerous - app in undefined state)
return false
})
}

// ============================================================
// DANGEROUS FUNCTION MONITORING
// ============================================================
// Hook common functions that indicate problems:
// - abort(): Explicit crash
// - __stack_chk_fail(): Stack buffer overflow detected
// - __assert_rtn(): Failed assertion
// - malloc/free: Memory allocation (can detect double-free, use-after-free)
// - memcpy/strcpy: Memory operations (can detect buffer overflows)
setupSignalHandlers() {
var crashFuncs = [
"abort",              // Explicit abort() call
"__stack_chk_fail",   // Stack canary check failed (buffer overflow)
"__assert_rtn",       // Assertion failure
"malloc",             // Memory allocation
"free",               // Memory deallocation
"memcpy",             // Memory copy
"strcpy"              // String copy
]

crashFuncs.forEach(function(funcName) {
try {
// Find the function in any loaded module (null = search all)
var addr = Module.findExportByName(null, funcName)
if (addr) {
Interceptor.attach(addr, {
onEnter: function(args) {
// Only log critical functions to avoid spam
if (funcName === "abort" || funcName === "__stack_chk_fail" || funcName === "__assert_rtn") {
console.log(`[!] ${funcName} called - potential crash imminent!`)
console.log("[!] Backtrace:")
// Show where this function was called from
Thread.backtrace(this.context, Backtracer.ACCURATE)
.map(DebugSymbol.fromAddress)
.slice(0, 5)
.forEach(function(s) { console.log(`    ${s}`) })
}
}
})
}
} catch (e) {
// Function not available on this platform, skip it
}
})
}

// ============================================================
// ARGUMENT CAPTURE HELPER
// ============================================================
// Generic method to capture any argument from a function call
// @param addr: Address of the function to monitor
// @param argIndex: Which argument to capture (0 = first, 1 = second, etc.)
// @param timeout: How long to wait (seconds) before giving up
captureArgument(addr, argIndex, timeout = 30) {
var captured = null
var attempts = 0
var maxAttempts = timeout * 10  // Check every 100ms

console.log(`[*] Capturing argument ${argIndex}...`)
console.log(`[*] Trigger the function in the app to capture its arguments`)

// Hook the function temporarily
var hook = Interceptor.attach(addr, {
onEnter: function(args) {
if (!captured && args[argIndex]) {
captured = new NativePointer(args[argIndex])
console.log(`[+] Captured arg[${argIndex}]: ${captured}`)
}
}
})

// Wait for a call to occur
while (!captured && attempts < maxAttempts) {
Thread.sleep(0.1)
attempts++
}

// Clean up the hook
hook.detach()

if (!captured) {
throw new Error(`Failed to capture argument ${argIndex} after ${timeout}s`)
}

return captured
}

// ============================================================
// FUZZ EXECUTION METHOD
// ============================================================
// Called by fpicker for each fuzzing iteration
// @param payload: Pointer to the mutated input data
// @param len: Length of the input in bytes
fuzz(payload, len) {
try {
// ============================================================
// STEP 1: Input validation
// ============================================================
// Reject unreasonably large inputs to prevent memory exhaustion
if (len > 1024 * 1024) { // 1MB limit
console.log(`[!] Payload too large: ${len} bytes, skipping`)
return
}

// ============================================================
// STEP 2: Prepare the fuzzed input
// ============================================================
// Allocate new memory and copy the payload
// Add null terminator for C string compatibility
var fuzz_data = Memory.alloc(len + 1)    // Allocate space + 1 byte for null
Memory.copy(fuzz_data, payload, len)     // Copy the payload
fuzz_data.add(len).writeU8(0)            // Add null terminator

// ============================================================
// STEP 3: Execute with timeout detection
// ============================================================
// Some inputs might cause infinite loops (hangs)
// Use a timer to detect when execution takes too long
var executed = false
var timer = setTimeout(function() {
if (!executed) {
console.log("[!] Execution timeout - possible hang")
// Note: This doesn't stop execution, just logs it
// Consider using Stalker or watchdog thread for true timeout
}
}, 5000) // 5 second timeout

// Call the target function
this.target_function(this.captured_ptr, this.tag, fuzz_data)

// Mark as completed and cancel timeout
executed = true
clearTimeout(timer)

} catch (e) {
// Exception occurred - likely a crash
console.log(`[!] Fuzz iteration exception: ${e.message}`)
throw e  // Re-throw for fpicker to handle
}
}
}

const fuzzer = new AdvancedFuzzer()
rpc.exports.fuzzer = fuzzer

Per usare l’advanced fuzzer:

# Compile the advanced fuzzer
frida-compile examples/target-app/advanced-fuzzer.js -o harness-advanced.js

# Run with automatic restart on crash using a wrapper script
cat > fuzz-with-restart.sh << 'EOF'
#!/bin/bash

APP_NAME="<Program to fuzz>"
OUTPUT_DIR="examples/target-app/out"
INPUT_DIR="examples/target-app/in"
HARNESS="harness-advanced.js"

while true; do
echo "[*] Starting fuzzing session at $(date)"

# Run fpicker (will exit on crash)
fpicker -v --fuzzer-mode active -e attach -p "$APP_NAME" -D usb \
-o "$OUTPUT_DIR" -i "$INPUT_DIR" -f "$HARNESS" \
--standalone-mutator cmd --mutator-command "radamsa"

EXIT_CODE=$?
echo "[!] Fuzzer exited with code $EXIT_CODE"

if [ $EXIT_CODE -ne 0 ]; then
echo "[*] Crash detected, saving crash info..."
echo "Crash at $(date)" >> "$OUTPUT_DIR/crash_log.txt"

# Kill the app if still running
killall "$APP_NAME" 2>/dev/null

# Wait for app to fully stop
sleep 2

# Restart the app
echo "[*] Restarting app..."
frida -U -f "$APP_NAME" --no-pause &
sleep 3
else
echo "[*] Fuzzing session completed normally"
break
fi
done
EOF

chmod +x fuzz-with-restart.sh
./fuzz-with-restart.sh

Semplice Fuzzer Standalone (senza fpicker)

Per test di fuzzing rapidi senza la configurazione di fpicker, usa questo script standalone:

// ============================================================
// SIMPLE STANDALONE FUZZER
// ============================================================
// This fuzzer works without fpicker - just load it with Frida
// Usage: frida -U -l simple-fuzzer.js <Program>
//
// This is great for:
// - Quick fuzzing tests
// - When you can't set up fpicker
// - Testing if a function is fuzzable
// - Learning how fuzzing works

console.log("[*] Simple Fuzzer starting...")

// ============================================================
// CONFIGURATION
// ============================================================
const TARGET_MODULE = "<Program>"          // Your app's main binary name
const TARGET_FUNCTION = "<function_name>"  // The function to fuzz
const ITERATIONS = 1000                    // How many times to fuzz
const MAX_PAYLOAD_SIZE = 1024              // Maximum size for random payloads

// Helper to build ArrayBuffer from byte array
function bytesToBuffer(bytes) {
var buffer = new ArrayBuffer(bytes.length)
var view = new Uint8Array(buffer)
for (var i = 0; i < bytes.length; i++) {
view[i] = bytes[i]
}
return buffer
}

// Helper to convert ASCII string into byte array (lossy for non-ASCII)
function stringToBytes(str) {
var bytes = []
for (var i = 0; i < str.length; i++) {
bytes.push(str.charCodeAt(i) & 0xff)
}
return bytes
}

// ============================================================
// MUTATION STRATEGIES
// ============================================================
// This function implements various fuzzing mutation strategies
// Each strategy targets different types of vulnerabilities
// Returns an object describing the mutation so we can handle
// both text and binary payloads safely
function mutatePayload(seed) {
var mutations = [
// Strategy 1: Buffer overflow - very long strings
function() {
return { type: "string", value: "A".repeat(Math.floor(Math.random() * 10000)), description: "Long 'A' string" }
},

// Strategy 2: Format string bugs
function() {
return { type: "string", value: "%s%s%s%s%s%s%s%s%s%s%n%n%n%n", description: "Format string" }
},

// Strategy 3: Null bytes and boundary characters
function() {
return {
type: "binary",
value: bytesToBuffer([0, 0, 0].concat(stringToBytes(seed), [0xff, 0xff, 0xff])),
description: "Boundary chars"
}
},

// Strategy 4: SQL injection patterns
function() {
return { type: "string", value: "' OR '1'='1", description: "SQL injection" }
},

// Strategy 5: XSS/script injection patterns
function() {
return { type: "string", value: "<script>alert(1)</script>", description: "XSS payload" }
},

// Strategy 6: Path traversal
function() {
return { type: "string", value: "../../../etc/passwd", description: "Path traversal" }
},

// Strategy 7: Invalid Unicode sequences
function() {
// Build deliberately malformed UTF sequence (includes null)
return {
type: "binary",
value: bytesToBuffer([0x00, 0xef, 0xff, 0xed, 0xa0, 0x80]),
description: "Invalid Unicode"
}
},

// Strategy 8: Extremely long repeated input
function() {
return { type: "string", value: seed.repeat(100), description: "Repeated seed" }
},

// Strategy 9: Null byte injection
function() {
return {
type: "binary",
value: bytesToBuffer(stringToBytes(seed).concat([0, 0, 0, 0])),
description: "Null byte injection"
}
},

// Strategy 10: Completely random bytes (binary payload)
function() {
var len = Math.floor(Math.random() * MAX_PAYLOAD_SIZE)
var bytes = []
for (var i = 0; i < len; i++) {
bytes.push(Math.floor(Math.random() * 256))
}
return { type: "binary", value: bytesToBuffer(bytes), description: `Random ${len}-byte buffer` }
}
]

// Randomly select one mutation strategy
return mutations[Math.floor(Math.random() * mutations.length)]()
}

// ============================================================
// FIND TARGET FUNCTION
// ============================================================
const target_addr = Module.findExportByName(TARGET_MODULE, TARGET_FUNCTION)
if (!target_addr) {
console.log("[!] Target function not found!")
console.log("[*] Available functions (first 20):")
Module.enumerateExports(TARGET_MODULE).slice(0, 20).forEach(function(exp) {
console.log(`    - ${exp.name}`)
})
throw new Error("Function not found")
}

console.log(`[+] Found target at ${target_addr}`)

// ============================================================
// CREATE FUNCTION WRAPPER
// ============================================================
// Wrap the native function so we can call it from JavaScript
// Adjust signature if your function has different parameters
const target_func = new NativeFunction(
target_addr,
"void",                              // Return type
["pointer", "pointer", "pointer"],   // Argument types
{}
)

// ============================================================
// CAPTURE REQUIRED ARGUMENTS
// ============================================================
// Many functions need a context pointer or handle
// We capture it from a real call instead of guessing
var captured_arg = null
console.log("[*] Waiting to capture arguments...")
console.log("[*] Please trigger the function in the app!")

var hook = Interceptor.attach(target_addr, {
onEnter: function(args) {
if (!captured_arg) {
captured_arg = new NativePointer(args[0])
console.log(`[+] Captured arg: ${captured_arg}`)
}
}
})

// Wait for the function to be called
while (!captured_arg) {
Thread.sleep(0.1)
}
hook.detach()

// ============================================================
// START FUZZING LOOP
// ============================================================
console.log(`[*] Starting ${ITERATIONS} fuzzing iterations...`)
var tag = Memory.allocUtf8String("FUZZ")  // Static second argument
var crashes = 0
var startTime = Date.now()

for (var i = 0; i < ITERATIONS; i++) {
var mutation = null
var payload_ptr = null
var payload_length = 0
var payload_preview = ""

try {
// ========================================================
// GENERATE MUTATED INPUT
// ========================================================
mutation = mutatePayload("Hello World")

if (mutation.type === "string") {
payload_length = mutation.value.length
payload_ptr = Memory.allocUtf8String(mutation.value)
payload_preview = mutation.value
} else {
payload_length = mutation.value.byteLength
var mem = Memory.alloc(payload_length + 1)
Memory.writeByteArray(mem, mutation.value)
mem.add(payload_length).writeU8(0)
payload_ptr = mem
payload_preview = hexdump(mem, { offset: 0, length: Math.min(payload_length, 32) })
}

// ========================================================
// EXECUTE TARGET FUNCTION
// ========================================================
target_func(captured_arg, tag, payload_ptr)

// ========================================================
// PROGRESS REPORTING
// ========================================================
if ((i + 1) % 100 == 0) {
var elapsed = (Date.now() - startTime) / 1000
var rate = (i + 1) / elapsed
console.log(`[*] Progress: ${i + 1}/${ITERATIONS} (${rate.toFixed(2)} exec/s) | Last mutation: ${mutation.description}`)
}

} catch (e) {
// ========================================================
// CRASH DETECTED
// ========================================================
crashes++
console.log(`\n[!] CRASH at iteration ${i}`)
console.log(`[!] Mutation: ${mutation ? mutation.description : 'Unknown'}`)
console.log(`[!] Exception: ${e.message}`)
console.log(`[!] Payload length: ${payload_length} bytes`)
try {
console.log(`    Preview (truncated):\n${payload_preview}`)
} catch (err) {
console.log(`    (Could not display payload preview)`)
}

// Note: After a crash, app state might be corrupted
// Ideally should restart app here, but that's complex in simple fuzzer
}
}

// ============================================================
// FINAL STATISTICS
// ============================================================
var elapsed = (Date.now() - startTime) / 1000
console.log(`\n[+] Fuzzing complete!`)
console.log(`    Iterations: ${ITERATIONS}`)
console.log(`    Crashes: ${crashes}`)
console.log(`    Crash rate: ${((crashes / ITERATIONS) * 100).toFixed(2)}%`)
console.log(`    Duration: ${elapsed.toFixed(2)}s`)
console.log(`    Rate: ${(ITERATIONS / elapsed).toFixed(2)} exec/s`)

if (crashes > 0) {
console.log(`\n[!] Found ${crashes} crashes!`)
console.log(`[*] Check iOS crash logs at:`)
console.log(`    /private/var/mobile/Library/Logs/CrashReporter/`)
}

Eseguilo con:

frida -U -l simple-fuzzer.js <Program>

Fuzzing Best Practices

1. Start with small corpus: Inizia con 3-5 input ben formati
2. Monitor memory: Usa Process.enumerateRanges() per controllare memory leak
3. Save interesting crashes: Controlla frequentemente /var/mobile/Library/Logs/CrashReporter/
4. Use coverage feedback: La modalità AFL++ in fpicker fornisce una copertura migliore
5. Timeout detection: Aggiungi timeout per rilevare hang (non solo crashes)
6. State restoration: Reimposta lo stato dell’app tra le iterazioni quando possibile
7. Multiple mutation strategies: Combina mutazioni random, format string e grammar-based fuzzing
8. Log systematically: Mantieni log dettagliati degli input che inducono crashes

Logs & Crashes

Puoi controllare la console di macOS o il log cli per consultare i log di macOS.
Puoi controllare anche i log di iOS usando idevicesyslog.
Alcuni log ometteranno informazioni mostrando <private>. Per visualizzare tutte le informazioni è necessario installare un profilo da https://developer.apple.com/bug-reporting/profiles-and-logs/ per abilitare quelle informazioni private.

Se non sai cosa fare:

vim /Library/Preferences/Logging/com.apple.system.logging.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Enable-Private-Data</key>
<true/>
</dict>
</plist>

killall -9 logd

Puoi controllare i crash in:

• iOS
• Impostazioni → Privacy → Analytics & Improvements → Analytics Data
• /private/var/mobile/Library/Logs/CrashReporter/
• macOS:
• /Library/Logs/DiagnosticReports/
• ~/Library/Logs/DiagnosticReports

Warning

iOS memorizza solo 25 crash della stessa app, quindi devi eliminarli o iOS smetterà di creare nuovi crash.

Ispezione e manipolazione della memoria

Scansiona e modifica la memoria del processo:

// frida -U <program> -l /tmp/memory-scan.js

console.log("[*] Memory scanning and manipulation tools loaded")

// Search for string in memory
function findString(searchString) {
console.log(`[*] Searching for: "${searchString}"`)
var results = []

Process.enumerateRanges('r--').forEach(function(range) {
try {
Memory.scan(range.base, range.size, searchString, {
onMatch: function(address, size) {
results.push(address)
console.log(`[+] Found at: ${address}`)

// Read context around the match
try {
var context = address.readUtf8String(50)
console.log(`    Context: "${context}"`)
} catch (e) {}
},
onComplete: function() {}
})
} catch (e) {
// Range not readable
}
})

console.log(`[*] Found ${results.length} occurrences`)
return results
}

// Search for byte pattern
function findBytes(pattern) {
console.log(`[*] Searching for byte pattern: ${pattern}`)
var results = []

Process.enumerateRanges('r--').forEach(function(range) {
try {
Memory.scan(range.base, range.size, pattern, {
onMatch: function(address, size) {
results.push(address)
console.log(`[+] Found at: ${address}`)

// Dump bytes
var bytes = address.readByteArray(16)
console.log(`    Bytes: ${hexdump(bytes, { length: 16 })}`)
},
onComplete: function() {}
})
} catch (e) {}
})

return results
}

// Dump memory region
function dumpMemory(address, size) {
try {
var addr = ptr(address)
var data = addr.readByteArray(size)
console.log(hexdump(data, { offset: 0, length: size, header: true, ansi: true }))
return data
} catch (e) {
console.log(`[!] Failed to read memory: ${e.message}`)
return null
}
}

// Write to memory
function patchMemory(address, bytes) {
try {
var addr = ptr(address)

// Save original bytes
var original = addr.readByteArray(bytes.length)
console.log("[*] Original bytes:")
console.log(hexdump(original))

// Write new bytes
addr.writeByteArray(bytes)
console.log("[+] Memory patched successfully")
console.log("[*] New bytes:")
console.log(hexdump(addr.readByteArray(bytes.length)))

return true
} catch (e) {
console.log(`[!] Failed to patch memory: ${e.message}`)
return false
}
}

// Watch memory region for changes
function watchMemory(address, size) {
var addr = ptr(address)
var original = addr.readByteArray(size)

console.log(`[*] Watching ${size} bytes at ${address}`)

setInterval(function() {
var current = addr.readByteArray(size)
if (JSON.stringify(original) !== JSON.stringify(current)) {
console.log(`[!] Memory changed at ${address}`)
console.log("[*] Old:")
console.log(hexdump(original, { length: Math.min(size, 64) }))
console.log("[*] New:")
console.log(hexdump(current, { length: Math.min(size, 64) }))
original = current
}
}, 1000)
}

// Enumerate loaded modules and their ranges
function enumerateModules() {
console.log("\n[*] Loaded modules:")
Process.enumerateModules().forEach(function(module) {
console.log(`\n  ${module.name}`)
console.log(`    Base: ${module.base}`)
console.log(`    Size: ${module.size}`)
console.log(`    Path: ${module.path}`)
})
}

// Find pointers to a specific address
function findPointers(targetAddress) {
var target = ptr(targetAddress)
var results = []

console.log(`[*] Searching for pointers to ${target}`)

Process.enumerateRanges('r--').forEach(function(range) {
try {
Memory.scan(range.base, range.size, target.toString().slice(2), {
onMatch: function(address, size) {
results.push(address)
console.log(`[+] Pointer found at: ${address}`)
},
onComplete: function() {}
})
} catch (e) {}
})

return results
}

// Protection utilities
function getProtection(address) {
var addr = ptr(address)
var ranges = Process.enumerateRanges('---')

for (var i = 0; i < ranges.length; i++) {
var range = ranges[i]
if (addr.compare(range.base) >= 0 &&
addr.compare(range.base.add(range.size)) < 0) {
return range.protection
}
}

return "unknown"
}

function changeProtection(address, size, protection) {
try {
Memory.protect(ptr(address), size, protection)
console.log(`[+] Changed protection at ${address} to ${protection}`)
return true
} catch (e) {
console.log(`[!] Failed to change protection: ${e.message}`)
return false
}
}

// Export functions for interactive use
rpc.exports = {
findString: findString,
findBytes: findBytes,
dumpMemory: dumpMemory,
patchMemory: patchMemory,
watchMemory: watchMemory,
enumerateModules: enumerateModules,
findPointers: findPointers,
getProtection: getProtection,
changeProtection: changeProtection
}

console.log("\n[+] Available functions:")
console.log("  - findString(str)")
console.log("  - findBytes(pattern)")
console.log("  - dumpMemory(address, size)")
console.log("  - patchMemory(address, [bytes])")
console.log("  - watchMemory(address, size)")
console.log("  - enumerateModules()")
console.log("  - findPointers(address)")
console.log("  - getProtection(address)")
console.log("  - changeProtection(address, size, 'rwx')")

// Example usage:
// findString("password")
// dumpMemory("0x100000000", 256)
// patchMemory("0x100000000", [0x90, 0x90, 0x90])

Tutorial Frida per Android

Frida Tutorial

Riferimenti

• Great Reversing Training
• https://www.briskinfosec.com/blogs/blogsdetail/Getting-Started-with-Frida

Tip

Impara e pratica il hacking AWS:HackTricks Training AWS Red Team Expert (ARTE)
Impara e pratica il hacking GCP: HackTricks Training GCP Red Team Expert (GRTE) Impara e pratica il hacking Azure: HackTricks Training Azure Red Team Expert (AzRTE)

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