CVE-2008-3639 in CUPS
Summary
by MITRE
Heap-based buffer overflow in the read_rle16 function in imagetops in CUPS before 1.3.9 allows remote attackers to execute arbitrary code via an SGI image with malformed Run Length Encoded (RLE) data containing a small image and a large row count.
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Analysis
by VulDB Data Team • 08/18/2019
The vulnerability identified as CVE-2008-3639 represents a critical heap-based buffer overflow affecting the Common Unix Printing System CUPS software version 1.3.8 and earlier. This flaw exists within the read_rle16 function located in the imagetops component, which is responsible for processing SGI image format files. The vulnerability specifically manifests when processing Run Length Encoded data within SGI image files, creating a scenario where attackers can manipulate the image processing pipeline to execute arbitrary code on systems running vulnerable versions of CUPS.
The technical implementation of this vulnerability involves a fundamental flaw in input validation and memory management within the SGI image parsing routine. When the read_rle16 function encounters malformed RLE data, particularly in small images with artificially inflated row counts, it fails to properly validate the relationship between the declared image dimensions and the actual data structure. This mismatch allows attackers to craft SGI image files where the row count parameter exceeds the actual allocated memory buffer, leading to memory corruption that can be exploited to overwrite adjacent memory locations. The heap-based nature of the overflow means that the corrupted memory segments are allocated from the heap rather than the stack, making exploitation more complex but still highly effective.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise when exploited successfully. Attackers can leverage this vulnerability to gain arbitrary code execution privileges on systems running vulnerable CUPS versions, potentially leading to full system compromise, data exfiltration, or persistent backdoor installation. Since CUPS serves as the primary printing system for many Unix-like operating systems, including various Linux distributions and macOS, the attack surface is extensive and affects numerous enterprise and consumer environments. The remote nature of the exploit means that attackers do not require local access to the system, making this vulnerability particularly dangerous for networked environments where printing services are exposed to external networks.
This vulnerability aligns with CWE-121, heap-based buffer overflow, and maps to multiple ATT&CK techniques including T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation. The attack vector specifically corresponds to T1190 for exploitation of remote services, as the vulnerability allows remote code execution through the printing system. Organizations implementing CUPS for printing services face significant risk when running vulnerable versions, particularly in environments where print servers are accessible from untrusted networks or where users can submit print jobs from remote locations.
Mitigation strategies for CVE-2008-3639 require immediate patching of affected CUPS installations to version 1.3.9 or later, which contains the necessary fixes to properly validate SGI image data structures. System administrators should also implement network segmentation to limit access to printing services, disable unnecessary printing protocols, and monitor for suspicious print job submissions. Additional defensive measures include implementing strict file validation for print job submissions, configuring firewalls to restrict access to printing ports, and maintaining regular vulnerability assessments to identify other potential attack vectors within printing infrastructure. The vulnerability demonstrates the critical importance of proper input validation in image processing libraries and the potential consequences of inadequate memory management in widely deployed software components.