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.)
CWE-413 Base Draft
Improper Resource Locking
This vulnerability occurs when an application fails to properly lock a shared resource, such as a file or memory location, before performing operations that require exclusive access.
Definition
What is CWE-413?
This vulnerability occurs when an application fails to properly lock a shared resource, such as a file or memory location, before performing operations that require exclusive access.
Without a proper locking mechanism, concurrent threads or processes can read or modify the same resource simultaneously. This race condition violates the developer's assumption that the resource state is stable during the critical operation, leading to data corruption, crashes, or incorrect application behavior.
Detecting these subtle timing issues in complex, distributed systems is challenging. While SAST tools can flag potential patterns, Plexicus uses AI to analyze runtime context and suggest precise code fixes—like implementing mutexes or semaphores—automating remediation and saving significant manual review time.
Real-world impact
Real-world CVEs caused by CWE-413
-
Chain: an operating system kernel has insufficent resource locking (CWE-413) leading to a use after free (CWE-416).
How attackers exploit it
Step-by-step attacker path
- 1
The following function attempts to acquire a lock in order to perform operations on a shared resource.
- 2
However, the code does not check the value returned by pthread_mutex_lock() for errors. If pthread_mutex_lock() cannot acquire the mutex for any reason, the function may introduce a race condition into the program and result in undefined behavior.
- 3
In order to avoid data races, correctly written programs must check the result of thread synchronization functions and appropriately handle all errors, either by attempting to recover from them or reporting them to higher levels.
- 4
This Java example shows a simple BankAccount class with deposit and withdraw methods.
- 5
However, the deposit and withdraw methods have shared access to the account balance private class variable. This can result in a race condition if multiple threads attempt to call the deposit and withdraw methods simultaneously where the account balance is modified by one thread before another thread has completed modifying the account balance. For example, if a thread attempts to withdraw funds using the withdraw method before another thread that is depositing funds using the deposit method completes the deposit then there may not be sufficient funds for the withdraw transaction.
Vulnerable code example
Vulnerable C
The following function attempts to acquire a lock in order to perform operations on a shared resource.
void f(pthread_mutex_t *mutex) {
pthread_mutex_lock(mutex);
```
/* access shared resource */*
pthread_mutex_unlock(mutex);} Secure code example
Secure C
In order to avoid data races, correctly written programs must check the result of thread synchronization functions and appropriately handle all errors, either by attempting to recover from them or reporting them to higher levels.
int f(pthread_mutex_t *mutex) {
int result;
result = pthread_mutex_lock(mutex);
if (0 != result)
return result;
```
/* access shared resource */*
return pthread_mutex_unlock(mutex);} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-413
- Architecture and Design Use a non-conflicting privilege scheme.
- Architecture and Design / Implementation Use synchronization when locking a resource.
Detection signals
How to detect CWE-413
CWE-413
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Frequently asked questions What is CWE-413?
How serious is CWE-413?
What languages or platforms are affected by CWE-413?
How can I prevent CWE-413?
How does Plexicus detect and fix CWE-413?
Where can I learn more about CWE-413?
Frequently asked questions
What is CWE-413?
This vulnerability occurs when an application fails to properly lock a shared resource, such as a file or memory location, before performing operations that require exclusive access.
How serious is CWE-413?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-413?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-413?
Use a non-conflicting privilege scheme. Use synchronization when locking a resource.
How does Plexicus detect and fix CWE-413?
Plexicus's SAST engine matches the data-flow signature for CWE-413 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-413?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/413.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-413
CWE-667 Parent
Improper Locking
This vulnerability occurs when a program fails to correctly acquire or release a lock on a shared resource, such as a file, database…
CWE-1232 Sibling
Improper Lock Behavior After Power State Transition
This vulnerability occurs when a hardware lock bit, designed to protect critical system configuration registers, is improperly reset or…
CWE-1233 Sibling
Security-Sensitive Hardware Controls with Missing Lock Bit Protection
This vulnerability occurs when a hardware device uses a lock bit to protect critical configuration registers, but the lock fails to…
CWE-1234 Sibling
Hardware Internal or Debug Modes Allow Override of Locks
Hardware debug modes or internal states can bypass critical system lock protections, allowing unauthorized changes to device configuration.
CWE-412 Sibling
Unrestricted Externally Accessible Lock
This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or…
CWE-414 Sibling
Missing Lock Check
This vulnerability occurs when software fails to verify that a proper synchronization lock is active before accessing or modifying a…
CWE-609 Sibling
Double-Checked Locking
Double-checked locking is an insufficient synchronization pattern where a program checks a resource's state, acquires a lock, and checks…
CWE-764 Sibling
Multiple Locks of a Critical Resource
This vulnerability occurs when a critical resource, such as a file, data structure, or connection, is locked more times than the software…
CWE-765 Sibling
Multiple Unlocks of a Critical Resource
This vulnerability occurs when a critical resource, like a lock or semaphore, is unlocked more times than it was locked, putting the…
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