CVE-2018-5345 in gcab
Summary
by MITRE
A stack-based buffer overflow within GNOME gcab through 0.7.4 can be exploited by malicious attackers to cause a crash or, potentially, execute arbitrary code via a crafted .cab file.
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Analysis
by VulDB Data Team • 01/20/2023
The CVE-2018-5345 vulnerability represents a critical stack-based buffer overflow flaw in the GNOME gcab library version 0.7.4 and earlier. This vulnerability resides within the CAB file parsing functionality of the gcab utility, which is widely used for handling Microsoft Cabinet archive files in Linux environments. The flaw manifests when the library processes malformed or specially crafted CAB files that contain oversized data structures within their headers or compressed data sections. The buffer overflow occurs due to insufficient bounds checking during the parsing of archive metadata, particularly when handling the extraction of file names, directory structures, or compressed content lengths. This vulnerability is particularly concerning as it affects the core functionality of the gcab library that many applications and system components rely upon for archive handling operations.
The technical exploitation of this vulnerability involves crafting a malicious CAB file that contains oversized buffer allocations in its internal structure. When the gcab library attempts to parse such a file, the lack of proper input validation causes the program to write data beyond the allocated stack buffer boundaries. This overflow can overwrite adjacent memory locations including return addresses, function pointers, and local variables. The vulnerability can be triggered through normal file processing operations when a user opens or extracts a CAB archive, making it particularly dangerous in environments where automated archive extraction occurs. The flaw is classified as a CWE-121 Stack-based Buffer Overflow, which directly maps to the ATT&CK technique T1059.007 for Command and Scripting Interpreter, as exploitation could lead to arbitrary code execution. The vulnerability is particularly severe because it can be exploited without requiring special privileges, as the buffer overflow occurs in a library that may be invoked by various user-level applications.
The operational impact of CVE-2018-5345 extends beyond simple denial of service scenarios to potentially enable remote code execution in vulnerable environments. Systems that automatically process or extract CAB files from untrusted sources become particularly vulnerable, including web servers, email clients, file sharing applications, and automated build systems that handle Microsoft Office documents or Windows installer packages. The vulnerability affects not only desktop environments but also server-side applications that utilize the gcab library for archive processing. When exploited successfully, the buffer overflow could allow attackers to execute arbitrary code with the privileges of the user running the vulnerable application, potentially leading to complete system compromise. The vulnerability is especially dangerous in enterprise environments where automated file processing pipelines may inadvertently process malicious archives, and it demonstrates the critical importance of input validation in archive handling libraries. The flaw affects the broader GNOME ecosystem and any software that depends on the gcab library for CAB file manipulation, making it a widespread security concern across Linux distributions that utilize this library for various archive processing tasks.
Mitigation strategies for CVE-2018-5345 should focus on immediate patching of the gcab library to version 0.7.5 or later, which includes proper bounds checking and input validation fixes. Organizations should implement strict file validation procedures for any CAB files that are processed automatically, including sandboxed execution environments for archive extraction. Network administrators should consider implementing file type restrictions and content scanning for CAB files in email attachments, web downloads, and file transfer systems. The implementation of application whitelisting policies can help prevent execution of vulnerable applications until proper patches are applied. System administrators should also monitor for any signs of exploitation attempts through unusual file processing patterns or memory access violations. Additionally, deploying intrusion detection systems that can identify suspicious CAB file structures and monitoring network traffic for malicious archive content can provide early warning capabilities. The vulnerability highlights the importance of maintaining up-to-date software libraries and implementing defense-in-depth strategies for archive processing operations, as the flaw could be exploited through multiple attack vectors including web-based delivery, email attachments, or file sharing systems. Organizations should also consider implementing automated patch management processes to ensure rapid deployment of security updates for critical library components like gcab.