CVE-2015-6673 in libpgf
Summary
by MITRE
Use-after-free vulnerability in Decoder.cpp in libpgf before 6.15.32.
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Analysis
by VulDB Data Team • 12/29/2022
The CVE-2015-6673 vulnerability represents a critical use-after-free flaw discovered in the libpgf library version 6.15.32 and earlier. This vulnerability specifically affects the Decoder.cpp component within the library, which is responsible for processing Portable Graphics Format files. The issue arises from improper memory management practices where freed memory blocks are still being accessed or referenced after they have been deallocated by the program. Such memory corruption vulnerabilities are particularly dangerous because they can lead to arbitrary code execution when an attacker successfully manipulates the program flow through controlled memory access patterns.
The technical nature of this vulnerability stems from a classic memory safety issue where the decoder function fails to properly track the lifecycle of allocated memory objects. When processing malformed or specially crafted PGF files, the library may free memory resources while still maintaining references to them, creating a use-after-free condition. This condition allows attackers to potentially overwrite freed memory with malicious data, leading to unpredictable program behavior and potential exploitation. The vulnerability manifests during the decoding process when the library encounters specific file structures that trigger the improper memory management sequence.
From an operational impact perspective, this vulnerability presents significant security risks to systems that utilize libpgf for graphics processing or document handling. The use-after-free condition could be exploited by attackers who craft malicious PGF files designed to trigger the vulnerable code path during normal file processing operations. This exploitation could result in remote code execution, denial of service, or information disclosure depending on the specific implementation and target environment. The vulnerability affects applications that rely on libpgf for image rendering, document conversion, or graphics processing workflows, making it particularly concerning for web applications, document management systems, and multimedia processing platforms.
The mitigation strategy for CVE-2015-6673 primarily involves updating to libpgf version 6.15.32 or later, which contains the necessary patches to address the memory management issues in Decoder.cpp. Organizations should prioritize this update across all systems that utilize libpgf libraries, particularly those exposed to untrusted input sources such as web applications or document processing services. Additionally, implementing proper input validation and sanitization measures can provide defense-in-depth protection against potential exploitation attempts. Security teams should also monitor for any related vulnerabilities in the broader graphics processing ecosystem and consider implementing runtime protections such as address space layout randomization and stack canaries to reduce exploitability. This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and could potentially map to ATT&CK technique T1059 for command and control through code execution, though the initial exploitation vector would more likely be through file-based attacks or web application vulnerabilities.