CVE-2017-11550 in libid3tag
Summary
by MITRE
The id3_ucs4_length function in ucs4.c in libid3tag 0.15.1b allows remote attackers to cause a denial of service (NULL Pointer Dereference and application crash) via a crafted mp3 file.
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Analysis
by VulDB Data Team • 12/14/2022
The vulnerability identified as CVE-2017-11550 resides within the libid3tag library version 0.15.1b, specifically in the id3_ucs4_length function located in the ucs4.c source file. This library serves as a critical component for parsing and handling id3 metadata tags within mp3 audio files, making it an essential element in multimedia applications and media players that process audio content. The flaw manifests as a null pointer dereference condition that occurs when processing malformed or crafted mp3 files, creating a remote denial of service scenario that can compromise the stability of applications relying on this library. The vulnerability represents a classic example of insufficient input validation where the function fails to properly handle edge cases in unicode string length calculations, particularly when dealing with UCS-4 encoded data structures.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious mp3 file containing specially formatted id3 tags with malformed UCS-4 encoding sequences. When the vulnerable id3_ucs4_length function attempts to calculate the length of these malformed unicode strings, it encounters a null pointer reference that leads to an application crash. This behavior stems from inadequate error checking and bounds validation within the function's implementation, where it assumes certain pointer values will not be null while processing the id3 tag data. The function's failure to properly validate input parameters before dereferencing pointers creates a predictable crash scenario that can be reliably triggered through crafted media files. This type of vulnerability aligns with CWE-476 which specifically addresses null pointer dereference conditions, and demonstrates poor defensive programming practices that are commonly exploited in denial of service attacks.
The operational impact of CVE-2017-11550 extends beyond simple application crashes to potentially disrupt media processing pipelines and audio playback services. Any application that utilizes libid3tag for id3 metadata parsing becomes vulnerable to this attack, including media players, audio streaming services, music libraries, and content management systems. The remote nature of the vulnerability means that attackers can exploit it without requiring local access to the target system, making it particularly dangerous in web-based environments where users may unknowingly download and process malicious media files. The vulnerability can be leveraged to create persistent service disruption scenarios, where attackers repeatedly submit crafted files to cause repeated crashes, effectively rendering affected services unavailable to legitimate users. This aligns with ATT&CK technique T1499.004 which describes network denial of service attacks targeting application availability.
Mitigation strategies for CVE-2017-11550 should focus on immediate library updates and input validation improvements. The most effective solution involves upgrading to a patched version of libid3tag that properly handles null pointer conditions and implements robust input validation for id3 tag parsing. Organizations should also implement defensive programming measures including null pointer checks before dereferencing any pointers in the id3 tag processing code, implementing proper bounds checking for unicode string operations, and adding comprehensive error handling routines. Additionally, input sanitization mechanisms should be deployed at network boundaries to filter out potentially malicious mp3 files before they reach applications that rely on libid3tag. The vulnerability demonstrates the importance of following secure coding practices and adhering to standards such as those outlined in the CERT secure coding guidelines, particularly in handling string operations and pointer dereferences. System administrators should also consider implementing monitoring and alerting mechanisms to detect unusual application crash patterns that may indicate exploitation attempts.