Vulnerability identifier: #VU48928

Vulnerability risk: High

CVSSv3.1: 8.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2020-6018

CWE-ID: CWE-121

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Game Networking Sockets
Client/Desktop applications / Games

Vendor: Valve Software

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error when processing long encrypted messages within the AES_GCM_DecryptContext::Decrypt() function. A remote unauthenticated attacker can send specially crafted messages to the application, trigger a stack-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Game Networking Sockets: 1.0.0 - 1.1.0

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External links
http://github.com/ValveSoftware/GameNetworkingSockets/commit/bea84e2844b647532a9b7fbc3a6a8989d66e49e3
http://research.checkpoint.com/2020/game-on-finding-vulnerabilities-in-valves-steam-sockets/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.