vuln-crypto

name: vuln-crypto description: "Scan for cryptographic failure vulnerabilities (weak algorithms, key management, TLS issues). Appends to vulnerabilities.md." allowed-tools: Read Bash(find *) Bash(grep *) Bash(head *) Bash(wc *) Bash(cat *) Bash(ls *) Write argument-hint: <path to threat-model.md, defaults to ./assessment/threat-model.md>

Bug Bounty — Step 3i: Cryptographic Failures

Scan for weak or misused cryptography that could lead to data exposure or integrity bypass.

Input

$ARGUMENTS

• Read ./assessment/threat-model.md (or provided path) for priority targets
• Read ./assessment/recon.md for entry points and data flows
• If either is missing, tell the user which step to run first

Vulnerability Patterns

Weak Algorithms

• MD5/SHA1 used for integrity or password hashing
• DES/3DES/RC4 for encryption
• RSA with key < 2048 bits
• ECB mode usage

Grep patterns: md5, sha1, DES, 3DES, RC4, ECB, createHash, createCipher, crypto.subtle

Improper Key Management

• Hardcoded encryption keys/IVs
• Static or predictable IVs/nonces
• Keys derived from weak sources (timestamps, sequential)
• Keys stored alongside encrypted data
• Missing key rotation

Grep patterns: key =, iv =, nonce =, SECRET_KEY, ENCRYPTION_KEY, AES_KEY, Buffer.from(, createCipheriv

TLS/Transport Issues

• TLS verification disabled (rejectUnauthorized: false, verify=False)
• Allowing outdated TLS versions (TLS 1.0/1.1)
• Self-signed certificate acceptance in production
• Mixed content (HTTP resources on HTTPS pages)

Grep patterns: rejectUnauthorized, verify=False, CERT_NONE, InsecureRequestWarning, ssl, tls, https, NODE_TLS_REJECT_UNAUTHORIZED

Random Number Generation

• Math.random() for security-sensitive values (tokens, IDs)
• Predictable seed values
• Non-CSPRNG for cryptographic operations

Grep patterns: Math.random, random.random, rand(), srand, crypto.randomBytes, secrets., os.urandom

Encryption Misuse

• Encryption without authentication (no HMAC/GCM)
• Padding oracle potential (CBC without MAC-then-encrypt)
• Reused nonces in stream ciphers/GCM
• Custom crypto implementations

Grep patterns: encrypt(, decrypt(, AES, GCM, CBC, CTR, HMAC, createSign, createVerify

Process

For each priority target from threat-model.md:

1. Identify crypto usage — find all encryption, hashing, signing, and random generation calls
2. Assess algorithm strength — are algorithms current and appropriate for their use case?
3. Check key handling — are keys properly generated, stored, and rotated?
4. Verify transport security — is TLS properly enforced and validated?
5. Assess impact — data decryption, forgery, integrity bypass

Output

Append to ./assessment/vulnerabilities.md:

# Vulnerability Findings — Cryptographic Failures

**Date**: {date}
**Scanner**: vuln-crypto

## Findings

### VULN-CRYPTO-001: {Title}

**Severity**: {Critical/High/Medium/Low}
**Confidence**: {High/Medium/Low}
**Category**: {Weak Algorithm / Key Management / TLS Issue / Weak RNG / Encryption Misuse}
**Location**: `{file}:{line}`
**CWE**: CWE-{327|321|326|330|328}

**Description**:
{What the vulnerability is}

**Vulnerable Code**:
```{lang}
{code snippet}
`` `

**Attack Scenario**:
1. {Step-by-step exploitation}

**Impact**:
{What attacker gains — data decryption, token forgery, MITM}

**Remediation**:
```{lang}
{fixed code}
`` `

---

Positive Observations

While scanning, note any strong security patterns relevant to this scanner's domain. Add them to the # Positive Security Observations section at the end of vulnerabilities.md:

- {scanner-name}: {what the codebase does well in this area}

Rules

• Only report crypto weaknesses with real impact — MD5 for cache keys is not a vuln; MD5 for passwords is.
• Context matters — assess whether the crypto protects sensitive data or security-critical operations.
• Include what the correct algorithm/approach should be.
• Idempotent output — if vulnerabilities.md already has a # Vulnerability Findings — Cryptographic Failures section, replace it entirely. See sc3-vuln-scan idempotency rule.
• Save to ./assessment/vulnerabilities.md and confirm.