CWE-558

Variant Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Draft MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE
Use of getlogin() in Multithreaded Application

Description

The product uses the getlogin() function in a multithreaded context, potentially causing it to return incorrect values.

The getlogin() function returns a pointer to a string that contains the name of the user associated with the calling process. The function is not reentrant, meaning that if it is called from another process, the contents are not locked out and the value of the string can be changed by another process. This makes it very risky to use because the username can be changed by other processes, so the results of the function cannot be trusted.

Consequences

Integrity, Access Control, Other — Modify Application Data, Bypass Protection Mechanism, Other

Mitigations

Phase: Architecture and Design

Using names for security purposes is not advised. Names are easy to forge and can have overlapping user IDs, potentially causing confusion or impersonation.

Phase: Implementation

Use getlogin_r() instead, which is reentrant, meaning that other processes are locked out from changing the username.

Detection

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)