CVE-2012-4025 in squashfs
Summary
by MITRE
Integer overflow in the queue_init function in unsquashfs.c in unsquashfs in Squashfs 4.2 and earlier allows remote attackers to execute arbitrary code via a crafted block_log field in the superblock of a .sqsh file, leading to a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability described in CVE-2012-4025 represents a critical integer overflow flaw within the unsquashfs utility, which is part of the Squashfs filesystem implementation. This issue affects versions 4.2 and earlier, making it a long-standing security concern that has impacted numerous systems relying on squashfs file extraction capabilities. The vulnerability specifically resides in the queue_init function within the unsquashfs.c source file, where improper handling of integer values creates a pathway for malicious code execution.
The technical exploitation mechanism involves a crafted block_log field within the superblock of a .sqsh file, which triggers an integer overflow condition. When unsquashfs processes this malformed input, the integer overflow results in a heap-based buffer overflow, fundamentally compromising the memory layout of the application. This type of vulnerability falls under CWE-190, which specifically addresses integer overflow conditions that can lead to buffer overflows and arbitrary code execution. The flaw demonstrates how seemingly benign file format parsing can become a vector for severe security breaches when proper input validation and integer boundary checks are absent.
Operationally, this vulnerability presents a significant risk to systems that process untrusted squashfs files, particularly those used in software distribution, containerization, or embedded systems. Attackers can remotely craft malicious .sqsh files that, when processed by unsquashfs, will cause the application to crash or more dangerously, execute arbitrary code with the privileges of the user running the extraction utility. The impact extends beyond simple application crashes to potential full system compromise, especially in environments where unsquashfs is used in automated processes or with elevated privileges. This vulnerability aligns with ATT&CK technique T1059.007 for execution through scripting and T1021.002 for remote service exploitation.
Mitigation strategies for CVE-2012-4025 require immediate patching of affected systems to Squashfs version 4.3 or later, which contains the necessary fixes for the integer overflow condition. System administrators should also implement strict file validation procedures for squashfs files, particularly those received from untrusted sources, and consider deploying sandboxed environments for file processing. Network-level controls can be implemented to prevent the automatic processing of squashfs files, while application-level defenses should include input sanitization and memory protection mechanisms such as stack canaries and address space layout randomization. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all systems running affected versions of Squashfs and ensure proper patch management protocols are in place to prevent similar issues from arising in the future.