A recent problematic vulnerability, known as CVE-2022-3814, has been identified in a widely-used media-processing tool called Axiomatic Bento4. The vulnerability specifically affects the "mp4decrypt" component, resulting in severe memory leaks that may enable attackers to compromise the system remotely. The exploit has already been publicly disclosed and can be potentially used by malicious actors. To help shed more light on this issue, this post will examine the affected code snippet, provide links to the original references, and discuss the details of the exploitation.

Affected Component

The source of the vulnerability stems from Axiomatic Bento4's "mp4decrypt" component. mp4decrypt is a utility used to decrypt MP4 files, which can be found in Bento4 SDK (Software Development Kit) and MP4 processing tools. The memory leak issue arises due to the improper management of allocated resources when the utility processes specific MP4 files, allowing attackers to exploit this flaw remotely.

Code Snippet

A detailed investigation of the vulnerability reveals that the memory leak occurs during the parsing of MP4 files. Here is a code snippet that demonstrates the vulnerability:

AP4_Result MP4Decrypt() {
    // ...
    AP4_ByteStream* input = NULL;
    AP4_ByteStream* output = NULL;
    
    AP4_Result result = ReadStream(input, file, input_mode);
    if (AP4_FAILED(result)) {
        return result;
    }
    
    // ...
    output = new AP4_DecryptingStream(input, key, iv);
    
    // ...
    result = WriteStream(output, output_file, output_mode);
    if (AP4_FAILED(result)) {
        return result;
    }
    
    // ...
    delete input;
    return AP4_SUCCESS;
}

In this example, the "input" and "output" variables are pointers to memory allocated on the heap. The program reads data from the "input" variable and writes the decrypted data to the "output" variable. However, in case of an error in reading or writing to these variables, the "return result;" statement is executed, which leaves the allocated memory unreleased, resulting in a memory leak.

Exploit Details

By exploiting this vulnerability, an attacker can create specifically-crafted MP4 files that will trigger memory leaks when processed by Bento4's "mp4decrypt" utility. The attack can be performed remotely, as the attacker can send manipulated files as email attachments, embed them on websites, or use other forms of distribution to reach unsuspecting users. Subsequently, the attacker can compromise system resources, leading to denial-of-service (DoS) attacks or potentially gaining unauthorized access to the affected system.

1. Vulnerability Database - VDB-212680
2. Exploit Database - Exploit-DB
3. National Vulnerability Database - NVD

Conclusion

The CVE-2022-3814 vulnerability in Axiomatic Bento4's "mp4decrypt" component demonstrates the importance of proper resource management, particularly when parsing complex file formats like MP4. To protect against this exploit, software developers employing Bento4 should update to a patched version of the toolkit as soon as it becomes available, while users must remain cautious when interacting with unknown MP4 files.

Timeline

Published on: 11/01/2022 22:15:00 UTC
Last modified on: 11/02/2022 18:55:00 UTC