Performing Cryptographic Audit of Application

Overview

A cryptographic audit systematically reviews an application's use of cryptographic primitives, protocols, and key management to identify vulnerabilities such as weak algorithms, insecure modes, hardcoded keys, insufficient entropy, and protocol misconfigurations. This skill covers building an automated crypto audit tool that scans Python and configuration files for common cryptographic weaknesses.

When to Use

• When conducting security assessments that involve performing cryptographic audit of application
• When following incident response procedures for related security events
• When performing scheduled security testing or auditing activities
• When validating security controls through hands-on testing

Prerequisites

• Familiarity with cryptography concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Objectives

• Detect usage of deprecated algorithms (MD5, SHA-1, DES, RC4)
• Identify insecure cipher modes (ECB) and padding schemes
• Find hardcoded keys, passwords, and secrets in source code
• Verify TLS/SSL configuration strength
• Check key derivation function parameters
• Validate random number generator usage
• Produce a structured audit report with findings and remediation

Key Concepts

Cryptographic Weakness Categories

Category	Examples	Risk Level
Weak Hashing	MD5, SHA-1 for integrity/signatures	High
Insecure Encryption	DES, 3DES, RC4, Blowfish	High
Bad Cipher Mode	ECB mode for any block cipher	High
Insufficient Key Size	RSA < 2048, AES-128 for long-term	Medium
Hardcoded Secrets	Keys/passwords in source code	Critical
Weak KDF	Low iteration PBKDF2, plain MD5	High
Poor Entropy	time-based seeds, predictable IVs	High
Deprecated Protocols	SSLv3, TLS 1.0, TLS 1.1	High

Security Considerations

• Review both application code and configuration files
• Check third-party dependencies for known crypto vulnerabilities
• Verify certificates and TLS configurations on deployed servers
• Ensure secrets are loaded from environment variables or vaults
• Review key storage and rotation practices

Validation Criteria

• Scanner detects all injected test weaknesses
• MD5/SHA-1 usage for security purposes is flagged
• ECB mode usage is flagged
• Hardcoded keys/passwords are detected
• Weak KDF parameters are identified
• Report includes severity, location, and remediation
• False positive rate is below 10%