CVE-2016-8694 in potrace
Summary
by MITRE
The bm_readbody_bmp function in bitmap_io.c in potrace before 1.13 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a crafted BMP image, a different vulnerability than CVE-2016-8695 and CVE-2016-8696.
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Analysis
by VulDB Data Team • 08/08/2020
The vulnerability identified as CVE-2016-8694 affects the potrace library version 1.12 and earlier, specifically within the bitmap_io.c file in the bm_readbody_bmp function. This represents a critical denial of service flaw that can be exploited remotely through the manipulation of BMP image files. The vulnerability arises from inadequate input validation and error handling mechanisms within the bitmap parsing routine, creating a scenario where maliciously crafted image data can trigger a null pointer dereference condition that ultimately results in application crash.
The technical implementation of this vulnerability stems from the function's failure to properly validate bitmap header structures and data offsets before attempting to access memory locations. When a malformed BMP file is processed, the bm_readbody_bmp function does not adequately check for null pointers or invalid memory references that could occur during the parsing of image data segments. This weakness aligns with CWE-476 which specifically addresses NULL pointer dereference vulnerabilities in software systems. The flaw demonstrates poor defensive programming practices where the code assumes valid input without proper validation checks, creating an attack surface that can be exploited by remote adversaries.
From an operational perspective, this vulnerability poses significant risks to systems that process or render BMP image files, particularly those utilizing the potrace library for vectorization operations. The remote exploitation capability means that attackers can trigger the denial of service condition without requiring local access or authentication, making it particularly dangerous in web applications, file processing services, or any environment where users can upload or submit BMP images. The crash condition results in complete service disruption, effectively preventing legitimate users from accessing the affected system or application functionality, which constitutes a substantial availability impact according to the CIA triad principles.
The impact extends beyond simple service interruption as this vulnerability can be leveraged in broader attack scenarios. Attackers might combine this flaw with other vulnerabilities to create more sophisticated attack vectors, or use it as a means to disrupt services in denial of service attacks. The vulnerability's classification under the ATT&CK framework would likely fall under the T1499 category for network denial of service, potentially combined with T1059 for command and control operations. Organizations should prioritize patching this vulnerability immediately, as it represents a straightforward exploitation path that does not require advanced technical skills or specialized tools. The recommended mitigation involves upgrading to potrace version 1.13 or later, where the input validation has been strengthened to prevent null pointer dereference conditions during BMP file processing. Additionally, implementing proper input sanitization measures and validating file formats before processing can provide additional defense in depth layers against similar vulnerabilities in other components of the system.