A recently disclosed vulnerability, CVE-2024-33063, can result in a Transient Denial of Service (DoS) attack on wireless networks. This is due to an issue in parsing the Management Frame Information Elements (ML IE) in beacons, which are packets sent by wireless Access Points (APs) to announce their presence to clients. The vulnerability triggers when the length of a Management Frame Information Element is greater than the actual length of the Info Element inside which it is embedded.

This article aims to provide a comprehensive analysis of the vulnerability and provide details on the exploit, code snippets and links to relevant references.

The Vulnerability - Overview

Modern wireless networks rely on various Information Elements (IE) to function correctly. Beacons, one of the most essential elements in a wireless network, contain several Information Elements that help devices connect and maintain a connection with the network. The issue arises due to improper parsing and processing of these elements, specifically the Management Frame Information Element (ML IE).

The vulnerability occurs when a specially-crafted malformed beacon is sent to a network device containing an ML IE whose info length is greater than the actual length of the element. As a result, the victim's network device crashes and experiences a Transient Denial of Service (DoS).

The following code snippet demonstrates the vulnerability

// Pseudo-code demonstrating the vulnerability
int parse_beacon_frame(uint8_t *frame_data, int frame_length) {
    int i = ;
    while (i < frame_length) {
        uint8_t element_id = frame_data[i++];
        uint8_t element_length = frame_data[i++];
        if (element_id == ML_IE_ID) {
            uint8_t ml_ie_common_info_length = frame_data[i++];
            if (element_length > ml_ie_common_info_length) {
                // This condition triggers the vulnerability
                return -1; // Error
            }
        }
        i += element_length;
    }
    
    return ;
}

Exploit Details

To exploit the vulnerability, an attacker may create a malformed beacon frame with the following characteristics:

The ML IE should be present inside the beacon frame.

2. The length of the common info of the ML IE should be greater than the actual length of the complete ML IE.

When a network device tries to parse this malformed beacon, it will experience a crash, resulting in a Transient Denial of Service (DoS).

To protect against this exploit, the code responsible for parsing and handling ML IEs needs to be fixed to not compute invalid lengths.

1. CVE Reference: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-33063
2. https://www.us-cert.gov/ncas/bulletins/SB22-yyyy - US-CERT's Vulnerability Bulletin

Conclusion

In summary, CVE-2024-33063 is a Transient Denial of Service (DoS) vulnerability that affects wireless networks due to improper parsing of Management Frame Information Elements (ML IE) inside beacon frames. It is crucial to deploy patches and fixes addressing this issue to maintain the stability of wireless networks and avoid potential service disruptions.

Timeline

Published on: 12/02/2024 11:15:08 UTC
Last modified on: 12/12/2024 15:26:19 UTC