CVE-2017-16797 in SWFTools
Summary
by MITRE
In SWFTools 0.9.2, the png_load function in lib/png.c does not properly validate an alloclen_64 multiplication of width and height values, which allows remote attackers to cause a denial of service (integer overflow, heap-based buffer overflow, and application crash) or possibly have unspecified other impact via a crafted PNG file.
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Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-16797 resides within SWFTools version 0.9.2, specifically in the png_load function located in lib/png.c. This issue represents a critical flaw in memory management and input validation that can be exploited by remote attackers through maliciously crafted PNG files. The vulnerability stems from inadequate validation of arithmetic operations involving image dimensions, creating a pathway for attackers to manipulate memory allocation parameters and potentially execute arbitrary code or cause system instability.
The technical root cause of this vulnerability lies in the improper handling of a 64-bit multiplication operation involving width and height values from PNG image headers. When the png_load function processes image dimensions, it fails to validate whether the multiplication of these values would result in an integer overflow or exceed safe memory allocation limits. This particular flaw falls under the CWE-190 category of Integer Overflow or Wraparound, which is classified as a fundamental weakness in software security that directly impacts memory safety. The multiplication of width and height values creates a calculated allocation size that, when unchecked, can result in heap-based buffer overflows when the application attempts to allocate memory for image processing.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more severe security consequences. Remote attackers can craft PNG files with maliciously large width and height values that, when processed by SWFTools, trigger integer overflow conditions. This overflow can cause the application to allocate insufficient memory for image data, leading to heap corruption and subsequent application crashes. Additionally, the vulnerability may allow for unspecified other impacts that could include information disclosure, privilege escalation, or execution of arbitrary code depending on the specific implementation details and system configuration. The vulnerability affects any system running SWFTools 0.9.2 that processes untrusted PNG files, making it particularly dangerous in web applications or services that handle user-uploaded image content.
Mitigation strategies for CVE-2017-16797 should prioritize immediate patching of SWFTools to a version that properly validates image dimensions before memory allocation occurs. Organizations should implement input validation measures that enforce reasonable limits on image dimensions and ensure that all arithmetic operations involving image size parameters are properly checked for overflow conditions. The ATT&CK framework categorizes this type of vulnerability under T1203 - Exploitation for Client Execution, as it involves manipulating application behavior through crafted input files. System administrators should also consider implementing network-level controls to restrict access to SWFTools processing functions and monitor for unusual memory allocation patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of following secure coding practices that include proper integer overflow checking, as recommended in industry standards such as the CERT Secure Coding Standards, which specifically address the risks associated with unchecked arithmetic operations in memory management contexts.