logo

CWE-828 - Signal Handler with Functionality that is not Asynchronous-Safe

CWE-828

  • Abstraction:
  • Variant
  • Structure:
  • Simple
  • Status:
  • Incomplete
Weakness Name

Signal Handler with Functionality that is not Asynchronous-Safe

Description

The product defines a signal handler that contains code sequences that are not asynchronous-safe, i.e., the functionality is not reentrant, or it can be interrupted.

This can lead to an unexpected system state with a variety of potential consequences depending on context, including denial of service and code execution. Signal handlers are typically intended to interrupt normal functionality of a program, or even other signals, in order to notify the process of an event. When a signal handler uses global or static variables, or invokes functions that ultimately depend on such state or its associated metadata, then it could corrupt system state that is being used by normal functionality. This could subject the program to race conditions or other weaknesses that allow an attacker to cause the program state to be corrupted. While denial of service is frequently the consequence, in some cases this weakness could be leveraged for code execution. There are several different scenarios that introduce this issue: Note that in some environments or contexts, it might be possible for the signal handler to be interrupted itself. If both a signal handler and the normal behavior of the product have to operate on the same set of state variables, and a signal is received in the middle of the normal execution's modifications of those variables, the variables may be in an incorrect or corrupt state during signal handler execution, and possibly still incorrect or corrupt upon return.

Common Consequences

Scope: Integrity, Confidentiality, Availability

Impact: DoS: Crash, Exit, or Restart, Execute Unauthorized Code or Commands

Notes: The most common consequence will be a corruption of the state of the product, possibly leading to a crash or exit. However, if the signal handler is operating on state variables for security relevant libraries or protection mechanisms, the consequences can be far more severe, including protection mechanism bypass, privilege escalation, or information exposure.

Related Weaknesses
  • Release Date:
  • 2010-12-13
  • Latest Modification Date:
  • 2023-06-29

Free security scan for your website