CVE-2022-3409 - Denial of Service Vulnerability in OpenBMC Project's bmcweb due to Inadequate Handling of Unclosed HTTP Headers

In the OpenBMC Project, a vulnerability has been identified in the bmcweb component that can allow an attacker to cause a denial of service (DoS) condition. This issue was discovered during the mitigation process for CVE-2022-2809, when the multipart_parser code was fuzzed using AFL++ with address sanitizer enabled to detect the smallest possible memory corruptions. A problem was identified with how the multipart_parser handles unclosed HTTP headers. By passing a long enough HTTP header without a colon in a multipart form, a one-byte overwrite occurs on the heap, which can be conducted multiple times in a loop and ultimately lead to a DoS attack.

Code Snippet

// multipart_parser.cpp - Affected code snippet
void multipart_parser::handle_header_field(std::string_view data) {
    // ...
    // data: a long unclosed HTTP header without a colon
    // ...
}

How the Exploit Works

The code snippet above demonstrates the affected part of the multipart parser. When a long, unclosed HTTP header without a colon is passed in the multipart form, the multipart_parser fails to handle the data properly, leading to a one-byte overwrite on the heap. By executing this action multiple times in a loop, an attacker could cause a DoS condition on the OpenBMC system.

Links to Original References

1. OpenBMC Project: https://www.openbmc.org/
2. bmcweb Repository: https://github.com/openbmc/bmcweb
3. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-3409
4. CWE-130: Improper Handling of Length Parameter Inconsistency: https://cwe.mitre.org/data/definitions/130.html

Steps to Reproduce the Exploit

To reproduce this vulnerability and observe the effects of the one-byte overwrite on the heap, follow these steps:

Compile the bmcweb component with an address sanitizer to find the memory corruptions.

3. Create a test program that utilizes the affected multipart_parser code and sends a long, unclosed HTTP header without a colon in a loop.

Mitigation and Recommendations

As of writing this post, no official patch has been made available to fix this vulnerability. However, some possible mitigation techniques include:

Ensuring that malformed HTTP headers are correctly handled without corrupting memory.

3. Periodically monitoring system logs and detecting any suspicious activity indicative of a DoS attack.

Conclusion

This post highlights the denial of service vulnerability (CVE-2022-3409) found in the OpenBMC Project's bmcweb component, allowing an attacker to cause a DoS condition by exploiting a one-byte overwrite on the heap. It is crucial for developers and system administrators to stay informed, apply patches when necessary, and implement robust security measures to prevent such exploits from causing significant damage.

Timeline

Published on: 10/27/2022 13:15:00 UTC
Last modified on: 10/31/2022 13:14:00 UTC