The software 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.
Extended Description
This prevents the software 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.
Time of Introduction
Architecture and Design
Implementation
Applicable Platforms
Languages
All
Common Consequences
Scope
Effect
Availability
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.
Detection Factors
White Box:
Automated code analysis techniques might not be able to reliably
detect this weakness, since the application's behavior and general
security model dictate which resource locks are critical. Interpretation
of the weakness might require knowledge of the environment, e.g. if the
existence of a file is used as a lock, but the file is created in a
world-writable directory.
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.
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.
Potential Mitigations
Phase
Description
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.
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.
Description
