CVE-2017-14222 in FFmpeg
Summary
by MITRE
In libavformat/mov.c in FFmpeg 3.3.3, a DoS in read_tfra() due to lack of an EOF (End of File) check might cause huge CPU and memory consumption. When a crafted MOV file, which claims a large "item_count" field in the header but does not contain sufficient backing data, is provided, the loop would consume huge CPU and memory resources, since there is no EOF check inside the loop.
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Analysis
by VulDB Data Team • 12/28/2022
The vulnerability identified as CVE-2017-14222 represents a critical denial of service weakness within FFmpeg's media processing library, specifically in the mov.c module version 3.3.3. This flaw resides in the read_tfra() function which handles the parsing of time frequency tables within MOV format files, a widely used container format for multimedia content. The issue stems from insufficient input validation mechanisms that fail to verify the existence of sufficient data beyond the declared header parameters, creating a scenario where maliciously crafted media files can trigger excessive resource consumption.
The technical implementation of this vulnerability occurs when a specially constructed MOV file contains an inflated "item_count" field in its header structure that declares a significantly larger number of items than actually exist in the file's data section. During the parsing process, the read_tfra() function enters a loop that iterates based on this declared count without performing any end-of-file checks. This absence of boundary validation allows the processing loop to continue indefinitely, consuming substantial computational resources as it attempts to access non-existent data structures. The flaw operates at the protocol parsing layer, making it particularly dangerous as it can be triggered simply by opening or processing a malicious file, without requiring any additional user interaction or complex exploitation techniques.
The operational impact of CVE-2017-14222 extends beyond simple resource exhaustion, as it can effectively render systems unusable through sustained CPU and memory consumption. Attackers can leverage this vulnerability to perform resource exhaustion attacks against applications that utilize FFmpeg for media processing, including content management systems, video streaming platforms, and multimedia applications. The vulnerability is particularly concerning because it affects widely deployed software components and can be exploited through simple file manipulation, making it an attractive target for attackers seeking to disrupt services or cause system instability. This type of vulnerability aligns with CWE-129, which addresses improper validation of array indices, and represents a classic example of an unchecked loop termination condition that can lead to resource exhaustion attacks.
Mitigation strategies for CVE-2017-14222 should focus on implementing comprehensive input validation and boundary checking mechanisms within the affected FFmpeg components. System administrators and developers should prioritize updating to patched versions of FFmpeg where the read_tfra() function includes proper EOF checks and data validation before loop execution. Additionally, implementing resource limits and timeouts during media processing operations can help prevent complete system exhaustion even if the vulnerability is not fully patched. The fix typically involves adding conditional checks to ensure that the file contains sufficient data before proceeding with loop iterations, preventing the exploitation of inflated header values. Organizations should also consider implementing automated scanning mechanisms to detect and block suspicious media files that exhibit characteristics of this vulnerability, as recommended in ATT&CK technique T1499.001 for resource exhaustion attacks. This vulnerability demonstrates the critical importance of proper input validation in multimedia processing libraries and highlights the need for robust boundary checking mechanisms in protocol parsers to prevent similar issues from occurring in other software components.