CVE-2012-4024 in squashfs
Summary
by MITRE
Stack-based buffer overflow in the get_component function in unsquashfs.c in unsquashfs in Squashfs 4.2 and earlier allows remote attackers to execute arbitrary code via a crafted list file (aka a crafted file for the -ef option). NOTE: probably in most cases, the list file is a trusted file constructed by the program s user; however, there are some realistic situations in which a list file would be obtained from an untrusted remote source.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability identified as CVE-2012-4024 represents a critical stack-based buffer overflow flaw within the unsquashfs utility, specifically in the get_component function located in unsquashfs.c. This issue affects Squashfs versions 4.2 and earlier, where the vulnerability manifests when processing crafted list files that are typically provided through the -ef command line option. The flaw stems from inadequate input validation and bounds checking when handling component names extracted from these list files, creating a scenario where attacker-controlled data can overwrite adjacent stack memory locations.
The technical exploitation of this vulnerability occurs through manipulation of the list file format that unsquashfs processes during decompression operations. When unsquashfs encounters a crafted list file containing maliciously constructed component names, the get_component function fails to properly validate the length of input data before copying it to a fixed-size stack buffer. This classic buffer overflow condition allows an attacker to overwrite return addresses, function pointers, and other critical stack variables, potentially enabling arbitrary code execution with the privileges of the unsquashfs process. The vulnerability's severity is amplified by the fact that while list files are typically user-generated and trusted, there are legitimate scenarios where such files might originate from untrusted remote sources, making this attack vector particularly concerning for network-based exploitation.
The operational impact of CVE-2012-4024 extends beyond simple code execution, as it can lead to complete system compromise when unsquashfs is executed with elevated privileges or in environments where users might be tricked into processing malicious list files. Attackers could leverage this vulnerability to gain unauthorized access to systems, escalate privileges, or establish persistent backdoors through the execution of malicious payloads. The vulnerability's exploitation requires minimal prerequisites since unsquashfs is commonly available on Linux systems and often used in automated processes or by system administrators. This makes the attack surface particularly broad and the potential damage significant.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Squashfs versions to 4.3 or later, where the buffer overflow has been addressed through proper input validation and bounds checking. System administrators should also implement strict file access controls and input validation for any unsquashfs operations that process untrusted input, particularly when dealing with remote sources or user-supplied list files. The implementation of secure coding practices such as using safe string handling functions, implementing proper buffer size validation, and employing stack protection mechanisms can prevent similar issues in future development cycles. Additionally, organizations should consider employing runtime protection mechanisms and monitoring for unusual unsquashfs execution patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-121 Stack-based Buffer Overflow and can be mapped to ATT&CK technique T1059.007 for execution through command-line interfaces, highlighting the need for comprehensive security controls across multiple defensive layers.