CVE-2015-0247 in e2fsprogs
Summary
by MITRE
Heap-based buffer overflow in openfs.c in the libext2fs library in e2fsprogs before 1.42.12 allows local users to execute arbitrary code via crafted block group descriptor data in a filesystem image.
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Analysis
by VulDB Data Team • 04/16/2022
The vulnerability identified as CVE-2015-0247 represents a critical heap-based buffer overflow flaw within the libext2fs library component of e2fsprogs software suite. This issue specifically affects the openfs.c file where improper handling of block group descriptor data in filesystem images creates exploitable conditions for local privilege escalation. The vulnerability exists in versions of e2fsprogs prior to 1.42.12, making a substantial portion of deployed systems susceptible to exploitation.
The technical root cause stems from inadequate bounds checking when processing block group descriptor data structures within filesystem images. When the libext2fs library attempts to parse malformed or crafted block group descriptors, it fails to validate the size and structure of incoming data before performing memory allocation operations. This deficiency allows attackers to manipulate the heap memory layout by providing specially constructed filesystem images that trigger buffer overflow conditions. The flaw operates at the kernel level filesystem parsing layer, making it particularly dangerous as it can be exploited through filesystem mounting operations.
From an operational perspective, this vulnerability enables local attackers to execute arbitrary code with the privileges of the process handling filesystem operations, typically root or system-level permissions. The attack vector requires local access to a system since the vulnerability is triggered during filesystem image processing rather than network-based interactions. However, the impact extends beyond simple code execution as successful exploitation can lead to complete system compromise, privilege escalation, and potential persistence mechanisms. The vulnerability aligns with CWE-121 heap-based buffer overflow conditions and represents a classic example of insufficient input validation in system-level software components.
The exploitability of CVE-2015-0247 is particularly concerning given the widespread adoption of e2fsprogs across Linux distributions and Unix-like systems. Attackers can craft malicious filesystem images that, when mounted or processed by vulnerable systems, trigger the buffer overflow condition. This creates opportunities for privilege escalation attacks where local users can gain root access to compromised systems. The vulnerability also maps to ATT&CK technique T1068 which describes local privilege escalation through exploitation of software vulnerabilities, and T1547.001 which covers registry run keys and startup folder modifications that could be leveraged post-exploitation.
Mitigation strategies for this vulnerability center on immediate software updates to e2fsprogs version 1.42.12 or later, which contain the necessary patches to address the buffer overflow conditions. System administrators should also implement proper filesystem image validation procedures and avoid mounting untrusted filesystem images from unknown sources. Additional protective measures include restricting local user access to filesystem operations, monitoring for unusual filesystem mounting activities, and implementing security controls such as mandatory access controls or file integrity monitoring solutions. The vulnerability demonstrates the critical importance of maintaining up-to-date system software and highlights the need for robust input validation in system-level libraries that handle untrusted data sources.