Weakness · High
CWE-558: Use of getlogin() in Multithreaded Application
What it is
The product uses the getlogin() function in a multithreaded context, potentially causing it to return incorrect values.
- Severity (our rating)
- High
- Likelihood of exploit
- Not rated by MITRE
- Introduced during
- Implementation
- Exploited in the wild
- No CVE in CISA's catalog
In more detail
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.
What an attacker can do
- Modify Application Data (Integrity, Access Control, Other)
- Bypass Protection Mechanism (Integrity, Access Control, Other)
- Other (Integrity, Access Control, Other)
How to prevent it
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.
Implementation
- Use getlogin_r() instead, which is reentrant, meaning that other processes are locked out from changing the username.
How to find it
- 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.)
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Start freeSource: MITRE Common Weakness Enumeration, CWE version 4.19.1. CWE is a trademark of The MITRE Corporation.