CVE-2020-6019 in Game Networking Sockets
Summary
by MITRE • 11/13/2020
Valve's Game Networking Sockets prior to version v1.2.0 improperly handles inlined statistics messages in function CConnectionTransportUDPBase::Received_Data(), leading to an exception thrown from libprotobuf and resulting in a crash.
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Analysis
by VulDB Data Team • 12/07/2020
The vulnerability identified as CVE-2020-6019 affects Valve's Game Networking Sockets library, specifically impacting versions prior to v1.2.0. This issue resides within the CConnectionTransportUDPBase::Received_Data() function where the library fails to properly handle inlined statistics messages. The flaw represents a classic buffer over-read or improper input validation scenario that can be exploited to cause application instability. The vulnerability occurs during the processing of network traffic where statistics data is embedded within the UDP packets, and the library's handling of this data does not adequately validate or sanitize the incoming message structure before attempting to parse it through libprotobuf.
The technical execution of this vulnerability involves the manipulation of network packets containing malformed statistics data that triggers an exception within the libprotobuf library component. When the CConnectionTransportUDPBase::Received_Data() function processes these specially crafted packets, it attempts to deserialize the statistics message using protobuf parsing mechanisms without proper bounds checking or input validation. This leads to a thrown exception that propagates up through the call stack and ultimately results in an application crash. The vulnerability is classified as a software fault that stems from inadequate error handling and input validation practices, making it particularly dangerous in networked applications where remote code execution or denial of service attacks can be readily orchestrated.
From an operational impact perspective, this vulnerability creates a significant risk for any gaming platform or application that relies on Valve's Game Networking Sockets library for network communication. The crash condition can be triggered remotely through network packets, making it a potential vector for denial of service attacks against gaming servers or client applications. The vulnerability affects the stability and availability of networked gaming experiences, potentially disrupting player sessions and server operations. The exploitation requires minimal privileges and can be performed by any remote attacker who can send specially crafted UDP packets to the target system, making it particularly concerning for online gaming services that handle large volumes of network traffic.
The vulnerability aligns with CWE-129, which addresses improper validation of input ranges, and CWE-704, which covers improper handling of exceptions during message parsing. It also maps to ATT&CK technique T1203, which involves exploitation of remote services, and T1499, which encompasses network disruption attacks. Organizations utilizing affected versions of Game Networking Sockets should prioritize immediate patching to version 1.2.0 or later, which includes proper validation of statistics message structures before protobuf deserialization. Additional mitigations may include implementing network segmentation, deploying intrusion detection systems to monitor for suspicious UDP traffic patterns, and configuring firewalls to limit access to affected services. The fix implemented by Valve addresses the root cause by adding proper bounds checking and input validation to ensure that statistics messages are properly sanitized before being processed by the protobuf library components.