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.
Threat Mapped score: 1.9
Industry: Finiancial
Threat priority: P3 - Important (Medium)
CVE: CVE-2001-0682
Program can not execute when attacker obtains a mutex.
CVE: CVE-2002-1914
Program can not execute when attacker obtains a lock on a critical output file.
CVE: CVE-2002-1915
Program can not execute when attacker obtains a lock on a critical output file.
CVE: 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: CVE-2000-0338
Chain: predictable file names used for locking, allowing attacker to create the lock beforehand. Resultant from permissions and randomness.
CVE: CVE-2000-1198
Chain: Lock files with predictable names. Resultant from randomness.
CVE: 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.
| Phase | Note |
|---|---|
| Architecture and Design | N/A |
| Implementation | N/A |
Intro: This code tries to obtain a lock for a file, then writes to it.
Body: PHP by default will wait indefinitely until a file lock is released. If an attacker is able to obtain the file lock, this code will pause execution, possibly leading to denial of service for other users. Note that in this case, if an attacker can perform an flock() on the file, they may already have privileges to destroy the log file. However, this still impacts the execution of other programs that depend on flock().
function writeToLog($message){ $logfile = fopen("logFile.log", "a"); //attempt to get logfile lock if (flock($logfile, LOCK_EX)) { fwrite($logfile,$message); // unlock logfile flock($logfile, LOCK_UN); } else { print "Could not obtain lock on logFile.log, message not recorded\n"; } } fclose($logFile);