CVE-2019-12980 in libming
Summary
by MITRE
In Ming (aka libming) 0.4.8, there is an integer overflow (caused by an out-of-range left shift) in the SWFInput_readSBits function in blocks/input.c. Remote attackers could leverage this vulnerability to cause a denial-of-service via a crafted swf file.
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Analysis
by VulDB Data Team • 10/08/2023
The vulnerability identified as CVE-2019-12980 resides within the Ming library version 0.4.8, specifically within the SWFInput_readSBits function located in blocks/input.c. This flaw represents a critical integer overflow condition that occurs due to an out-of-range left shift operation, making it particularly dangerous for remote exploitation. The Ming library serves as a C library for creating and manipulating Shockwave Flash files, and this vulnerability directly impacts the library's ability to process malformed input data safely.
The technical implementation of this vulnerability stems from improper handling of bit manipulation operations within the SWF file parsing mechanism. When the SWFInput_readSBits function processes certain bitfield data, it performs a left shift operation on an integer value that exceeds the maximum representable value for the target data type. This overflow condition creates a scenario where the program's memory management becomes compromised, as the shifted value can wrap around to produce unexpected results. The vulnerability is particularly concerning because it operates at the core input parsing layer of the library, meaning any SWF file processed through this library could potentially trigger the overflow condition.
From an operational perspective, this vulnerability presents a significant denial-of-service risk for systems that rely on the Ming library for SWF file processing. Remote attackers can craft malicious SWF files that, when processed by applications using the vulnerable library, will cause the target system to crash or become unresponsive. The attack vector is particularly dangerous because SWF files are commonly distributed through web browsers and web applications, making the exploit surface wide and accessible. The integer overflow can lead to memory corruption, stack corruption, or other unstable program states that prevent normal operation of the affected applications.
The impact of this vulnerability extends beyond simple service disruption as it can potentially enable more sophisticated attacks depending on the environment where the vulnerable library is deployed. Systems processing SWF content from untrusted sources become prime targets for exploitation, particularly web servers, content management systems, and any application that handles SWF file uploads or processing. The vulnerability's classification aligns with CWE-190, which addresses integer overflow conditions, and can be mapped to ATT&CK technique T1203, which covers exploitation of remote services through input validation flaws. Organizations using the Ming library in production environments should consider this vulnerability as a critical security concern requiring immediate attention.
Mitigation strategies for CVE-2019-12980 should focus on immediate library updates to versions that address the integer overflow condition, along with implementing input validation measures that can detect and reject malformed SWF files before they reach the vulnerable parsing functions. Network-based defenses can include content filtering systems that scan SWF file uploads for suspicious patterns or implement sandboxing mechanisms to isolate SWF processing operations. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all applications and systems that depend on the Ming library, ensuring that proper patch management procedures are in place to address similar vulnerabilities in the future. The fix typically involves implementing proper bounds checking and integer range validation before performing bit shift operations, ensuring that the shift amount remains within acceptable limits for the target data type.