Objective 2.3High Priority10 min read

Cryptographic Vulnerabilities

Weaknesses in cryptographic implementations including use of deprecated algorithms, poor key management, implementation flaws, and protocol weaknesses that undermine the security cryptography is meant to provide.

Understanding Cryptographic Vulnerabilities

Cryptographic vulnerabilities occur when encryption fails to provide its intended protection. Even strong algorithms can be weakened by poor implementation, improper key management, or using outdated standards.

Key cryptographic vulnerability categories: • Weak or deprecated algorithms — Using broken or obsolete crypto • Poor key management — Keys exposed, never rotated, or too short • Implementation flaws — Bugs in crypto code • Protocol weaknesses — Vulnerable crypto protocols

The principle: cryptography is only as strong as its weakest implementation point.

Why This Matters for the Exam

Cryptographic vulnerabilities are tested throughout SY0-701 as they affect confidentiality and integrity. Questions cover algorithm status (deprecated vs. secure), key management, and protocol selection.

Understanding these vulnerabilities helps in security assessments—knowing what makes encryption weak allows you to identify issues and recommend fixes.

Real-world breaches often involve cryptographic failures: weak hashing, expired certificates, or deprecated protocols.

Deep Dive

Weak or Deprecated Algorithms

Using cryptographic algorithms that are no longer considered secure.

Algorithm Status:

CategorySecureDeprecatedBroken
SymmetricAES-128/192/2563DESDES, RC4
AsymmetricRSA-2048+, ECCRSA-1024RSA-512
HashingSHA-256, SHA-3SHA-1MD5
ProtocolsTLS 1.2/1.3TLS 1.0/1.1SSL 2.0/3.0

Why Algorithms Become Weak:

  • •Computing power increases
  • •Cryptographic attacks discovered
  • •Mathematical weaknesses found
  • •Quantum computing threats

Weak Algorithm Risks:

  • •Encrypted data can be decrypted
  • •Hashes can be collided
  • •Signatures can be forged
  • •Man-in-the-middle attacks succeed

Poor Key Management

Keys are the foundation of cryptography—poor management undermines everything.

Key Management Failures:

FailureRisk
Short keysBrute force feasible
Weak key generationPredictable keys
Key reuseOne compromise affects all
No rotationLonger exposure window
Poor storageKeys easily stolen
No revocationCompromised keys stay valid

Key Length Requirements:

  • •Symmetric: AES-128 minimum, 256 preferred
  • •RSA: 2048 minimum, 4096 for long-term
  • •ECC: 256-bit minimum

Key Management Best Practices:

  • •Use strong random number generators
  • •Store keys in HSM or secure key vault
  • •Rotate keys regularly
  • •Implement key revocation
  • •Separate keys by purpose
  • •Audit key access

Implementation Flaws

Bugs in cryptographic code that weaken security.

Common Implementation Errors:

Side-Channel Attacks:

  • •Timing differences reveal information
  • •Power analysis
  • •Cache timing attacks
  • •Example: Spectre exploits

Random Number Generation:

  • •Predictable "random" numbers
  • •Insufficient entropy
  • •Example: Debian OpenSSL bug (2008)

Memory Issues:

  • •Keys left in memory
  • •Heartbleed exposed memory contents
  • •Keys not zeroed after use

Padding Oracle:

  • •Error messages reveal padding validity
  • •Decrypt ciphertext byte by byte
  • •Example: POODLE attack

Initialization Vector (IV) Reuse:

  • •Using same IV multiple times
  • •Reveals plaintext relationships
  • •WEP completely broken by IV reuse

Protocol Vulnerabilities

Weaknesses in how cryptographic protocols are designed or configured.

Protocol Issues:

VulnerabilityDescription
Downgrade attacksForce use of weak protocol version
BEASTTLS 1.0 CBC vulnerability
POODLESSL 3.0 padding oracle
CRIME/BREACHCompression side channels
DROWNCross-protocol attack via SSLv2

Protocol Best Practices:

  • •Disable old protocol versions
  • •Use TLS 1.2 minimum, prefer 1.3
  • •Disable weak cipher suites
  • •Enable perfect forward secrecy
  • •Regular protocol audits

Certificate and PKI Vulnerabilities

Weaknesses in certificate management.

Certificate Issues:

  • •Expired certificates
  • •Self-signed in production
  • •Weak signature algorithms
  • •Private key exposure
  • •Improper validation

Certificate Best Practices:

  • •Monitor expiration dates
  • •Use trusted CAs for public services
  • •Revoke compromised certificates
  • •Use strong signature algorithms
  • •Implement certificate transparency

How CompTIA Tests This

Example Analysis

Scenario: A security audit reveals that a legacy application uses MD5 to hash passwords, stores encryption keys in a configuration file, and communicates via TLS 1.0. What cryptographic vulnerabilities exist?

Analysis - Multiple Cryptographic Vulnerabilities:

1. MD5 Password Hashing: • MD5 is cryptographically broken • Collision attacks are practical • Rainbow tables exist for MD5 • Passwords can be recovered • Fix: Use bcrypt, scrypt, or Argon2

2. Keys in Configuration File: • Keys stored in plaintext • Accessible to anyone with file access • No access control on keys • Fix: Use HSM or secure key vault

3. TLS 1.0: • Known vulnerabilities (BEAST, etc.) • Deprecated by industry standards • Non-compliant with PCI DSS • Fix: Upgrade to TLS 1.2 or 1.3

Risk Summary: • User credentials at risk (MD5) • Encryption keys easily stolen (poor storage) • Communication can be compromised (TLS 1.0)

Key insight: Multiple cryptographic weaknesses compound risk. Each vulnerability could enable attack, and together they leave the application highly exposed.

Key Terms to Know

cryptographic vulnerabilitiesweak encryptionkey managementcryptographic failuresdeprecated algorithmsimplementation flawsprotocol weaknesses

Common Mistakes to Avoid

Thinking any encryption is good enough—using deprecated algorithms like MD5 or DES provides false sense of security.
Ignoring key management—even AES-256 is useless if keys are stored in plaintext or easily guessed.
Using encryption without understanding—implementing crypto incorrectly (IV reuse, bad RNG) undermines security.
Not updating protocols—TLS 1.0/1.1 and SSL should be disabled. Use TLS 1.2 minimum.

Exam Tips

MD5 and SHA-1 are broken for security purposes (collisions possible).
DES is broken. 3DES is deprecated. AES is the symmetric standard.
RSA keys should be 2048 bits minimum. 4096 for high security.
TLS 1.3 is preferred. TLS 1.2 acceptable. TLS 1.0/1.1 deprecated. SSL is broken.
Keys must be properly generated, stored, rotated, and revoked.
Implementation flaws (IV reuse, bad RNG) break even strong algorithms.

Memory Trick

"AKIP" - Cryptographic Vulnerability Types

  • •Algorithm weakness (deprecated/broken crypto)
  • •Key management failures (poor key handling)
  • •Implementation flaws (coding bugs)
  • •Protocol vulnerabilities (TLS/SSL issues)
  • •Algorithm Status Memory:
  • •MD5/SHA-1 = Must Stop using
  • •DES = Dead
  • •3DES = "Nearing retirement at age 3"
  • •AES = Active and secure
  • •Key Management: "GEARS"
  • •Generate with strong RNG
  • •Encrypt at rest
  • •Audit access
  • •Rotate regularly
  • •Securely destroy when done

TLS Version Memory: 1.0/1.1 = Too old (deprecated) 1.2 = Two is okay 1.3 = Three is best

Test Your Knowledge

Q1.A security assessment finds that an application uses MD5 to hash user passwords. What is the PRIMARY concern?

Q2.What cryptographic vulnerability allows an attacker to force a connection to use an older, weaker protocol version?

Q3.An organization stores encryption keys in a plaintext configuration file accessible to application administrators. What is this an example of?

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