Weakness · High
CWE-831: Signal Handler Function Associated with Multiple Signals
What it is
The product defines a function that is used as a handler for more than one signal.
- 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
While sometimes intentional and safe, when the same function is used to handle multiple signals, a race condition could occur if the function uses any state outside of its local declaration, such as global variables or non-reentrant functions, or has any side effects. An attacker could send one signal that invokes the handler function; in many OSes, this will typically prevent the same signal from invoking the handler again, at least until the handler function has completed execution. However, the attacker could then send a different signal that is associated with the same handler function. This could interrupt the original handler function while it is still executing. If there is shared state, then the state could be corrupted. This can lead to a variety of potential consequences depending on context, including denial of service and code execution. Another rarely-explored possibility arises when the signal handler is only designed to be executed once (if at all). By sending multiple signals, an attacker could invoke the function more than once. This may generate extra, unintended side effects. A race condition might not even be necessary; the attacker could send one signal, wait until it is handled, then send the other signal.
What an attacker can do
- DoS: Crash, Exit, or Restart (Availability, Integrity, Confidentiality, Access Control, Other)
- Execute Unauthorized Code or Commands (Availability, Integrity, Confidentiality, Access Control, Other)
- Read Application Data (Availability, Integrity, Confidentiality, Access Control, Other)
- Gain Privileges or Assume Identity (Availability, Integrity, Confidentiality, Access Control, Other)
- Bypass Protection Mechanism (Availability, Integrity, Confidentiality, Access Control, Other)
- Varies by Context (Availability, Integrity, Confidentiality, Access Control, Other)
How to prevent it
MITRE lists no specific mitigation for this weakness. Treat it like its parent weaknesses below: validate input, keep the design simple and review the code where it could appear.
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Start freeSource: MITRE Common Weakness Enumeration, CWE version 4.19.1. CWE is a trademark of The MITRE Corporation.