CVE-2013-3571 in socat
Summary
by MITRE
socat 1.2.0.0 before 1.7.2.2 and 2.0.0-b1 before 2.0.0-b6, when used for a listen type address and the fork option is enabled, allows remote attackers to cause a denial of service (file descriptor consumption) via multiple request that are refused based on the (1) sourceport, (2) lowport, (3) range, or (4) tcpwrap restrictions.
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Analysis
by VulDB Data Team • 12/25/2024
The vulnerability identified as CVE-2013-3571 affects socat versions prior to 1.7.2.2 and 2.0.0-b6, representing a significant denial of service weakness in network communication utilities. This flaw manifests when socat operates in listen mode with the fork option enabled, creating a scenario where remote attackers can exploit specific network restrictions to consume excessive file descriptors. The vulnerability stems from inadequate handling of connection requests that are rejected due to various restriction criteria, leading to resource exhaustion that ultimately renders the system unavailable to legitimate users.
The technical implementation of this vulnerability involves socat's processing of network connections when it functions as a listener with forking capabilities. When multiple connection attempts are made that fail validation against sourceport, lowport, range, or tcpwrap restrictions, the application fails to properly clean up file descriptors associated with these rejected connections. This results in a gradual accumulation of open file descriptors that eventually exhaust system resources. The flaw operates through a combination of improper resource management and insufficient connection handling logic that fails to account for the cumulative effect of repeatedly rejected connections. According to CWE-400, this represents a resource leak vulnerability where the application does not properly release system resources, and the weakness aligns with CWE-1321 which addresses improper handling of connection requests in network services.
The operational impact of CVE-2013-3571 extends beyond simple service disruption to encompass broader system stability concerns. Attackers can systematically consume file descriptors through repeated connection attempts that are rejected based on the specified restrictions, effectively creating a resource exhaustion attack that can bring down the target system or service. This vulnerability is particularly dangerous in environments where socat serves as a network endpoint for critical services, as it can be exploited by anyone with network access to the affected system. The attack requires minimal privileges and can be executed through standard network connection attempts, making it an attractive vector for denial of service attacks. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 which covers network denial of service attacks, and T1566.001 which involves social engineering through network connections.
Mitigation strategies for CVE-2013-3571 focus primarily on updating socat to patched versions that properly handle rejected connection attempts and clean up associated file descriptors. System administrators should immediately upgrade to socat 1.7.2.2 or later versions, or 2.0.0-b6 and newer, to address the resource leak issue. Additional protective measures include implementing connection rate limiting, configuring proper firewall rules to restrict access to socat listener ports, and monitoring system file descriptor usage for abnormal increases. Network segmentation and access control lists can help limit exposure by restricting which systems can establish connections to socat listeners. The vulnerability also highlights the importance of proper resource management in network services and demonstrates how seemingly minor implementation flaws can lead to significant availability issues. Organizations should conduct vulnerability assessments to identify all instances of vulnerable socat versions and implement comprehensive monitoring to detect potential exploitation attempts.