CVE-2016-9824 in libav
Summary
by MITRE
Integer overflow in libswscale/x86/swscale.c in libav 11.8 allows remote attackers to cause a denial of service (crash) via a crafted file.
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Analysis
by VulDB Data Team • 09/03/2020
The vulnerability identified as CVE-2016-9824 represents a critical integer overflow condition within the libswscale library component of libav version 11.8. This flaw exists in the x86/swscale.c file and specifically affects the video scaling functionality that processes multimedia content. The integer overflow occurs when the library handles certain crafted input files, leading to unpredictable behavior that can result in application crashes. This vulnerability falls under the category of software security flaws that can be exploited remotely, making it particularly dangerous in networked environments where multimedia processing is common.
The technical implementation of this vulnerability stems from improper handling of integer arithmetic within the video scaling algorithms. When processing specially crafted multimedia files, the libswscale component performs calculations that exceed the maximum representable value for the integer data type being used. This overflow condition causes the application to allocate insufficient memory or attempt invalid memory operations, ultimately leading to a crash. The flaw is particularly insidious because it can be triggered through legitimate multimedia file processing operations without requiring special privileges or complex exploitation techniques. According to CWE classification, this vulnerability maps to CWE-190 Integer Overflow or Wraparound, which is a well-documented weakness that occurs when a calculation produces a result that is outside the range of values that can be represented by the target data type.
The operational impact of CVE-2016-9824 extends beyond simple denial of service, as it can be leveraged by attackers to disrupt multimedia processing services across various applications. Systems that rely on libav for video transcoding, streaming, or multimedia processing are particularly vulnerable, including content delivery networks, media servers, and multimedia applications. The remote exploitation capability means that attackers can trigger the vulnerability from outside the local network, making it a significant threat to organizations that process user-uploaded multimedia content. This vulnerability aligns with ATT&CK technique T1499.004 for Denial of Service through resource exhaustion, as the integer overflow can cause applications to crash repeatedly, consuming system resources and potentially rendering services unavailable to legitimate users.
Mitigation strategies for CVE-2016-9824 should focus on immediate patching of affected libav installations, as the vulnerability has been addressed in subsequent releases of the library. Organizations should implement comprehensive monitoring for unusual application crashes or processing failures that could indicate exploitation attempts. Input validation and sanitization measures should be enhanced to prevent malformed multimedia files from reaching the vulnerable library components. Additionally, network segmentation and access controls can help limit the potential impact of exploitation attempts, while regular security assessments should be conducted to identify other potential integer overflow vulnerabilities in multimedia processing libraries. The fix typically involves proper bounds checking and overflow detection mechanisms within the integer arithmetic operations that were previously vulnerable to this type of attack.