In 2022, security researchers uncovered a vulnerability that’s quite sneaky: CVE-2022-25676, discovered in multiple Qualcomm Snapdragon chipsets. This isn’t your average bug—it’s an information disclosure flaw hiding in the code that processes AVI video files. Let's break down what happened, how it can affect your device, and how the bug works at a technical level.

What is CVE-2022-25676?

CVE-2022-25676 is an information disclosure vulnerability found in the parsing of AVI video files using Qualcomm’s multimedia software. The affected products include:

Snapdragon Wear

This vulnerability arises due to a buffer over-read, which is a programming error where the app or driver accidentally reads more data than it should from a buffer (a block of memory used to store data temporarily).

In simple words:  
Imagine you're supposed to read a sentence, but you keep reading past the period into whatever comes next—which might be something sensitive!

Information Disclosure:

If an attacker tricks your device into opening a specially crafted AVI video file, the vulnerable software can leak information from process memory. Sometimes, this can include personal data, hidden information, or even security keys.

- Potential impact: Attackers can sneak a peek into memory areas they shouldn't access, possibly pulling out private data used elsewhere in the system.

Typical AVI File Parsing

When your Snapdragon device plays an AVI file, the driver uses C code to read chunks of the file. These chunks are stored in a buffer. The code is supposed to carefully read only within the buffer's bounds.

What Went Wrong

In affected versions, the software used a “read pointer" but failed to check if it’s safe to read the amount of bytes requested. If the AVI file tricks this logic, the app can read past the buffer's edge—spilling information from memory.

Pseudocode example of bad logic

void parse_avi_chunk(uint8_t *buffer, size_t buffer_size) {
    // Suppose we want to read 'chunk_size' from the buffer
    uint32_t chunk_size = read_uint32_from_file();

    // BAD: No proper bounds check before reading!
    uint8_t chunk[1024];
    memcpy(chunk, buffer, chunk_size); // Dangerous: what if chunk_size > buffer_size?
    // ... process chunk
}


*In the above code, if the attacker controls chunk_size and makes it bigger than buffer_size, the function overruns the buffer and reads arbitrary memory.*

Attacker crafts a malicious AVI file with tricky chunk sizes.

2. Victim opens the file with an affected Snapdragon-powered app, device, or gadget (possibly from a message, download, or web browser).
3. The vulnerable parser reads extra bytes from its own memory and possibly sends them wherever the attacker wants (e.g., via playback logging, crashed dump, or a connected device).

Practical Exploit Example

Here is a simple, conceptual Python script to illustrate how a malicious AVI file might try to exploit the bug by injecting a large size value in the AVI chunk header:

# WARNING: THIS IS FOR EDUCATIONAL PURPOSES ONLY!
with open('malicious.avi', 'wb') as avi:
    avi.write(b'RIFF')                       # RIFF header
    avi.write(b'\xFF\xFF\xFF\x7F')           # Insanely large file size
    avi.write(b'AVI ')                       # AVI identifier
    avi.write(b'JUNK')                       # AVI chunk header
    avi.write(b'\xFF\xFF\xFF\x7F')           # Chunk size set way too large
    avi.write(b'A' * 1024)                   # Some repeated data

*An AVI player with this bug would try to read past the data you supplied, possibly leaking adjoining memory contents.*

Qualcomm patched this in various chipset lines by adding proper boundary checks

if(chunk_size > buffer_size) {
    // error!
    return ERROR_OUT_OF_BOUNDS;
}
memcpy(chunk, buffer, chunk_size);

Qualcomm Security Bulletin (June 2022):

https://www.qualcomm.com/company/product-security/bulletins/june-2022-bulletin

CVE Details:

https://nvd.nist.gov/vuln/detail/CVE-2022-25676

Qualcomm Product Security:

https://www.qualcomm.com/company/product-security

Keep your device firmware up to date. Manufacturers often ship fixes in their software updates.

- Be careful opening video files from untrusted sources. A random video from a message or website could hide malicious payloads.
- Check security bulletins for your phone or device. If it uses Qualcomm Snapdragon, see if your model was listed as vulnerable.

Conclusion

CVE-2022-25676 might sound obscure, but it shows how even watching videos can become risky if device makers don’t check their code boundaries. This bug reminds us that parsing files safely is hard—and important. Always keep your devices updated, and remember that sometimes, even your videos can bite!


*Stay safe, keep your devices patched, and watch your (video) back!*

Timeline

Published on: 11/15/2022 10:15:00 UTC
Last modified on: 04/19/2023 17:10:00 UTC