CVE-2011-0761 in Perl
Summary
by MITRE
Perl 5.10.x allows context-dependent attackers to cause a denial of service (NULL pointer dereference and application crash) by leveraging an ability to inject arguments into a (1) getpeername, (2) readdir, (3) closedir, (4) getsockname, (5) rewinddir, (6) tell, or (7) telldir function call.
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Analysis
by VulDB Data Team • 10/12/2024
The vulnerability identified as CVE-2011-0761 represents a critical denial of service weakness in Perl 5.10.x versions that stems from improper handling of function arguments within specific system calls. This flaw manifests when attackers can inject malicious arguments into fundamental directory and socket operation functions, creating a scenario where the Perl interpreter encounters null pointer dereferences during execution. The vulnerability specifically affects seven distinct system calls including getpeername, readdir, closedir, getsockname, rewinddir, tell, and telldir, all of which are commonly used in network and file system operations within Perl applications.
The technical root cause of this vulnerability lies in the lack of proper input validation and argument sanitization within Perl's implementation of these system calls. When malicious arguments are injected into these functions, the underlying Perl interpreter fails to properly validate the input parameters before attempting to dereference pointers, leading to null pointer dereference exceptions. This type of flaw falls under CWE-476 which specifically addresses NULL pointer dereference conditions that can be exploited to cause application crashes and system instability. The vulnerability demonstrates a classic weakness in defensive programming where insufficient boundary checking and input validation creates exploitable paths for attackers to manipulate program execution flow.
From an operational perspective, this vulnerability presents significant risk to systems running Perl applications that interact with network services or file system operations. Attackers can leverage this weakness to cause repeated application crashes, leading to service disruption and potential denial of service conditions for legitimate users. The impact extends beyond simple application instability as system administrators may experience cascading failures when multiple processes or services relying on Perl crash simultaneously. The vulnerability is particularly concerning because these affected functions are fundamental to many network and file operations, making the attack surface broad and potentially affecting numerous enterprise applications.
The attack vector for this vulnerability requires context-dependent conditions where attackers must be able to inject arguments into the targeted system calls, typically through input that gets processed by Perl applications. This could occur through web application inputs, network communications, or file processing operations that pass user-controlled data to these vulnerable functions. According to ATT&CK framework, this vulnerability aligns with technique T1499.004 which involves network denial of service attacks, and T1595.001 which covers network scanning and enumeration activities that might lead to exploitation. Organizations should implement robust input validation mechanisms, ensure proper argument sanitization, and maintain up-to-date Perl installations to mitigate this risk. Additionally, monitoring for unusual application crash patterns and implementing proper error handling can help detect exploitation attempts and reduce the overall impact of such attacks on system availability.