Google gRPC HPACK Parser iteration

Summaryinfo

A vulnerability labeled as problematic has been found in Google gRPC. This impacts an unknown function of the component HPACK Parser. The manipulation results in iteration. This vulnerability is reported as CVE-2023-33953. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Google gRPC (the affected version unknown). It has been classified as problematic. Affected is an unknown part of the component HPACK Parser. The manipulation with an unknown input leads to a iteration vulnerability. CWE is classifying the issue as CWE-834. The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed. This is going to have an impact on availability. CVE summarizes:

gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ Three vectors were found that allow the following DOS attacks: - Unbounded memory buffering in the HPACK parser - Unbounded CPU consumption in the HPACK parser The unbounded CPU consumption is down to a copy that occurred per-input-block in the parser, and because that could be unbounded due to the memory copy bug we end up with an O(n^2) parsing loop, with n selected by the client. The unbounded memory buffering bugs: - The header size limit check was behind the string reading code, so we needed to first buffer up to a 4 gigabyte string before rejecting it as longer than 8 or 16kb. - HPACK varints have an encoding quirk whereby an infinite number of 0’s can be added at the start of an integer. gRPC’s hpack parser needed to read all of them before concluding a parse. - gRPC’s metadata overflow check was performed per frame, so that the following sequence of frames could cause infinite buffering: HEADERS: containing a: 1 CONTINUATION: containing a: 2 CONTINUATION: containing a: 3 etc…

The weakness was disclosed 08/09/2023 as gcp-2023-022. The advisory is shared for download at cloud.google.com. This vulnerability is traded as CVE-2023-33953 since 05/24/2023. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 212043 (RHEL 9 : rhc-worker-playbook (RHSA-2024:10761)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (212043). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Google

Name

• gRPC

License

• free

Website

• Vendor: https://www.google.com/

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Once again VulDB remains the best source for vulnerability data.

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