MASTG-TEST-0221 Broken Symmetric Encryption Algorithms (Android)

Platform: Android
Weakness: MASWE-0007
Weakness in the numbering of the MASWE beta: MASWE-0020
Profiles: L1 (basic security), L2 (advanced security)
Type: static, code, manual
Best practices: MASTG-BEST-0009

Overview

To test for the [use of broken encryption algorithms](../../../Document/0x04g-Testing-Cryptography.md#identifying-insecure-andor-deprecated-cryptographic-algorithms) in Android apps, we need to focus on methods from cryptographic frameworks and libraries that are used to perform encryption and decryption operations.

Cipher.getInstance): Initializes a Cipher object for encryption or decryption. The algorithm parameter can be one of the supported algorithms.
SecretKeyFactory.getInstance): Returns a SecretKeyFactory object that converts keys into key specifications and vice versa. The algorithm parameter can be one of the supported algorithms.
KeyGenerator.getInstance): Returns a KeyGenerator object that generates secret keys for symmetric algorithms. The algorithm parameter can be one of the supported algorithms.

Some broken symmetric encryption algorithms include:

DES (Data Encryption Standard): 56-bit key, breakable, withdrawn by NIST in 2005.
3DES (Triple DES, officially the Triple Data Encryption Algorithm (TDEA or Triple DEA)): 64-bit block size, vulnerable to Sweet32 birthday attacks, withdrawn by NIST on January 1, 2024.
RC4: Predictable key stream, allows plaintext recovery RC4 Weakness, disapproved by NIST in 2014 and prohibited by IETF in 2015.
Blowfish: 64-bit block size, vulnerable to Sweet32 attacks, never FIPS-approved, and listed under "Non-Approved algorithms" in FIPS.

Android also provides additional guidance on broken cryptographic algorithms.

Steps

Use MASTG-TECH-0013 to reverse engineer the app.
Use MASTG-TECH-0014 to look for the relevant APIs.

Observation

The output should contain a list of locations where insecure symmetric encryption algorithms are used.

Evaluation

The test case fails if you can find [insecure or deprecated](../../../Document/0x04g-Testing-Cryptography.md#identifying-insecure-andor-deprecated-cryptographic-algorithms) encryption algorithms being used.

Further Validation Required:

Inspect each reported code location using MASTG-TECH-0023 to determine whether the algorithm is used in a security-relevant context to protect sensitive data.

Linkede sager

Sagslinks
Linktype	Sag
is related to	MASTG-BEST-0009 Use Secure Encryption Algorithms (Android)

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