Name Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
Summary This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. A typical example is file access. The adversary can leverage a file access race condition by "running the race", meaning that they would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the adversary could replace or modify the file, causing the application to behave unexpectedly.
Prerequisites A resource is access/modified concurrently by multiple processes. The adversary is able to modify resource. A race condition exists while accessing a resource.
Solutions Use safe libraries to access resources such as files. Be aware that improper use of access function calls such as chown(), tempfile(), chmod(), etc. can cause a race condition. Use synchronization to control the flow of execution. Use static analysis tools to find race conditions. Pay attention to concurrency problems related to the access of resources.
Related Weaknesses
CWE ID Description
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-366 Race Condition within a Thread
CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-368 Context Switching Race Condition
CWE-370 Missing Check for Certificate Revocation after Initial Check
CWE-662 Improper Synchronization
CWE-663 Use of a Non-reentrant Function in a Concurrent Context
CWE-665 Improper Initialization
CWE-691 Insufficient Control Flow Management
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