CVE-2022-33239 Exploitation: Transient Denial of Service due to Loop with Unreachable Exit Condition in WLAN Firmware while Parsing IPv6 Extension Header Across Various Snapdragon Processors

Intro

The CVE-2022-33239 is a recently discovered security vulnerability affecting multiple Qualcomm Snapdragon platforms, including Snapdragon Auto, Snapdragon Compute, Snapdragon Connectivity, Snapdragon Consumer Electronics Connectivity, Snapdragon Consumer IOT, Snapdragon Industrial IOT, Snapdragon Mobile, Snapdragon Voice & Music, Snapdragon Wearables, and Snapdragon Wired Infrastructure and Networking.

This vulnerability is particularly concerning because it can lead to a transient denial of service (DOS) attack, which makes the target device temporarily unavailable, causing disruptions and disconnections. Specifically, the DOS attack occurs due to an infinite loop with an unreachable exit condition in the Wireless LAN (WLAN) firmware when handling the IPv6 extension header. In this post, we will take a closer look at CVE-2022-33239, including the vulnerable code snippet, original references, and exploit details.

Vulnerable Code Snippet

The exact source code of the issue in Snapdragon's WLAN firmware is not publicly available, but a generic code snippet can highlight the fundamental problem:

while (parsing_ipv6_ext_header) {
    // Parse the current extension header
    ...
  
    // Process the extension header
    ...
  
    // Check exit condition
    if (header_length >= max_length || next_header_type == FINAL_TYPE) {
        break;
    }
}

In this code snippet, an infinite loop occurs due to an unreachable exit condition - the loop will never exit if the maximum header length or final header type is not reached. This causes the CPU to consume resources indefinitely, resulting in a transient DOS.

For more information on CVE-2022-33239, please consult the following references

- The original CVE entry: MITRE CVE-2022-33239
- GitHub Issue: Wireless LAN firmware IPv6 extension header bug
- Vendor Advisory: Qualcomm Security Bulletin

Exploit Details

A potential exploit for CVE-2022-33239 might involve sending malicious IPv6 extension headers that trigger the infinite loop, causing a transient DOS on the target device. As an attacker, you would craft a series of IPv6 packets that include extension headers with loop-inducing characteristics, such as having headers with incomplete or deceptive length data, sending the target device into an infinite parsing loop.

To reproduce the exploit, an adversary might leverage a tool like Scapy to create malicious IPv6 packets:

from scapy.all import *

# Define the target
target = "fe80::200:f8ff:fe21:67cf"

# Craft the malicious IPv6 packets
mal_packet = IPv6(dst=target) / IPv6ExtHdrFragment()

# Send the malicious packet
send(mal_packet)

However, it is important to emphasize that attempting to exploit this vulnerability without proper authorization is illegal, and this example is solely for educational purposes.

Conclusion

The CVE-2022-33239 is a crucial security vulnerability affecting various Snapdragon platforms due to an infinite loop with an unreachable exit condition in the WLAN firmware caused by parsing IPv6 extension headers. This vulnerability can lead to transient DOS attacks, rendering the target device temporarily unavailable, causing service disruptions and connectivity loss.

Device manufacturers running Snapdragon chipsets should apply the necessary firmware updates as soon as possible to patch this vulnerability. Users are also advised to install any available security updates on their systems and ensure that their devices are protected from potential exploitation.

Timeline

Published on: 11/15/2022 10:15:00 UTC
Last modified on: 11/18/2022 05:04:00 UTC