CVE-2016-10056 in ImageMagick
Summary
by MITRE
Buffer overflow in the sixel_decode function in coders/sixel.c in ImageMagick before 6.9.5-8 allows remote attackers to cause a denial of service (application crash) or other unspecified impact via a crafted file.
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Analysis
by VulDB Data Team • 11/14/2022
The vulnerability identified as CVE-2016-10056 represents a critical buffer overflow flaw within ImageMagick's sixel decoding functionality, specifically in the coders/sixel.c file. This issue affects ImageMagick versions prior to 6.9.5-8 and presents a significant security risk due to its potential for remote code execution or system compromise. The vulnerability stems from inadequate input validation and memory management within the sixel_decode function, which processes SIXEL image format data. SIXEL is a graphics format that was historically used on terminals and early graphics systems, making this flaw particularly concerning given the widespread use of ImageMagick in web applications and server environments. The buffer overflow occurs when the application attempts to process malformed SIXEL data, leading to memory corruption that can result in unpredictable behavior. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory safety issues. The attack vector is particularly dangerous because it allows remote attackers to craft malicious files that, when processed by ImageMagick, trigger the buffer overflow condition.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as the buffer overflow can potentially be exploited to execute arbitrary code on affected systems. When a crafted SIXEL file is processed by ImageMagick, the sixel_decode function fails to properly bounds-check input data before copying it into fixed-size buffers. This allows attackers to overwrite adjacent memory locations, potentially corrupting program execution flow or injecting malicious code. The vulnerability's severity is amplified by ImageMagick's widespread deployment across web servers, content management systems, and file processing applications. Systems that process user-uploaded images or files containing embedded SIXEL data become prime targets for exploitation. The flaw can be leveraged in various attack scenarios including web application exploitation, where malicious files uploaded to vulnerable systems could trigger the buffer overflow, or through email attachments that, when opened by applications using ImageMagick, could cause system compromise. This vulnerability aligns with ATT&CK technique T1203, which covers exploitation for execution through the manipulation of memory, and represents a common pathway for privilege escalation attacks.
Mitigation strategies for CVE-2016-10056 primarily focus on immediate version updates and implementation of input validation measures. Organizations should prioritize upgrading to ImageMagick version 6.9.5-8 or later, which contains the necessary patches to address the buffer overflow condition in the sixel_decode function. Additionally, implementing strict input validation and sanitization protocols can significantly reduce the risk of exploitation. Security teams should consider deploying web application firewalls and content filtering systems that can detect and block suspicious SIXEL data patterns before they reach vulnerable ImageMagick processing components. Network segmentation and principle of least privilege configurations can limit the potential impact if exploitation occurs. The vulnerability also highlights the importance of comprehensive software supply chain security, as ImageMagick's use across multiple platforms makes this flaw particularly dangerous. Regular security assessments and penetration testing should include evaluation of image processing libraries and their handling of various file formats. Organizations utilizing ImageMagick should also implement monitoring solutions that can detect abnormal processing patterns or memory allocation behaviors that might indicate exploitation attempts. The fix implemented in the patched versions addresses the core memory management issue by introducing proper bounds checking and input validation mechanisms, preventing the buffer overflow condition from occurring during SIXEL data processing.