Unrestricted Externally Accessible Lock

Opis

The product properly checks for the existence of a lock, but the lock can be externally controlled or influenced by an actor that is outside of the intended sphere of control.

This prevents the product from acting on associated resources or performing other behaviors that are controlled by the presence of the lock. Relevant locks might include an exclusive lock or mutex, or modifying a shared resource that is treated as a lock. If the lock can be held for an indefinite period of time, then the denial of service could be permanent.

Skutki

• Availability

  DoS: Resource Consumption (Other)

  When an attacker can control a lock, the program may wait indefinitely until the attacker releases the lock, causing a denial of service to other users of the program. This is especially problematic if there is a blocking operation on the lock.

Zapobieganie

• Architecture and Design, Implementation

  Use any access control that is offered by the functionality that is offering the lock.

• Architecture and Design, Implementation

  Use unpredictable names or identifiers for the locks. This might not always be possible or feasible.

• Architecture and Design

  Consider modifying your code to use non-blocking synchronization methods.

Przykłady podatności

• CVE-2001-0682 Program can not execute when attacker obtains a mutex.
• CVE-2002-1914 Program can not execute when attacker obtains a lock on a critical output file.
• CVE-2002-1915 Program can not execute when attacker obtains a lock on a critical output file.
• CVE-2002-0051 Critical file can be opened with exclusive read access by user, preventing application of security policy. Possibly related to improper permissions, large-window race condition.
• CVE-2000-0338 Chain: predictable file names used for locking, allowing attacker to create the lock beforehand. Resultant from permissions and randomness.
• CVE-2000-1198 Chain: Lock files with predictable names. Resultant from randomness.
• CVE-2002-1869 Product does not check if it can write to a log file, allowing attackers to avoid logging by accessing the file using an exclusive lock. Overlaps unchecked error condition. This is not quite CWE-412, but close.

Słabość nadrzędna

• CWE-667 Improper Locking

Może też być

• CWE-410 Insufficient Resource Pool

Kiedy powstaje

• Architecture and Design
• Implementation

Dotyczy

Not Language-Specific

Uwagi

This overlaps Insufficient Resource Pool when the "pool" is of size 1. It can also be resultant from race conditions, although the timing window could be quite large in some cases.