• Platform: Android
• Weakness: MASWE-0027
• Weakness in the numbering of the MASWE beta: MASWE-0052
• Profiles: L1 (basic security), L2 (advanced security)
• Type: static, code
• Knowledge: MASTG-KNOW-0014

Overview

This test evaluates whether an Android app explicitly trusts user-added CA certificates by including <certificates src="user"/> in its Network Security Configuration which is defined android:networkSecurityConfig attribute is set in the <application> tag. Even though starting with Android 7.0 (API level 24) apps no longer trust user-added CAs by default, this configuration overrides that behavior.

Such trust can expose the application to [MITM attacks](../../../Document/0x04f-Testing-Network-Communication.md#intercepting-network-traffic-through-mitm), as malicious CAs installed by users could intercept secure communications.

Steps

1. Use MASTG-TECH-0013 to reverse engineer the app.
2. Use MASTG-TECH-0117 to obtain the AndroidManifest.xml.
3. Use MASTG-TECH-0150 to check if the android:networkSecurityConfig attribute is present.
4. Use MASTG-TECH-0151 to extract all uses of <certificates src="user" /> from the Network Security Configuration file.

Observation

The output should contain all the <trust-anchors> from the Network Security Configuration file along with any defined <certificates> entries, if present.

Evaluation

The test case fails if <certificates src="user" /> has been defined as part of the <trust-anchors> in the Network Security Configuration file.

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