CVE-2011-1316 in WebSphere Application Server
Summary
by MITRE
The Session Initiation Protocol (SIP) Proxy in the HTTP Transport component in IBM WebSphere Application Server (WAS) before 7.0.0.15 allows remote attackers to cause a denial of service (worker thread exhaustion and UDP messaging outage) by sending many UDP messages.
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Analysis
by VulDB Data Team • 10/19/2021
The vulnerability identified as CVE-2011-1316 affects IBM WebSphere Application Server versions prior to 7.0.0.15, specifically within the Session Initiation Protocol SIP Proxy functionality that operates over HTTP Transport. This represents a significant security flaw that can be exploited by remote attackers to disrupt service availability through strategic manipulation of UDP messaging protocols. The vulnerability resides in the server's handling of SIP proxy operations within the HTTP transport layer, creating a pathway for malicious actors to exploit the system's resource management mechanisms.
The technical flaw manifests through the improper handling of UDP messages within the SIP proxy component, where the system fails to adequately validate or limit incoming UDP traffic. When numerous UDP messages are transmitted to the vulnerable server, the system's worker threads become exhausted as they process these messages without sufficient rate limiting or resource allocation controls. This worker thread exhaustion directly impacts the server's ability to process legitimate requests and maintain normal UDP messaging operations. The vulnerability specifically targets the HTTP Transport component's SIP proxy implementation, which creates a unique attack vector that leverages the SIP protocol's messaging characteristics to overwhelm the underlying transport mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption to encompass complete UDP messaging outages within the affected system. Attackers can systematically consume available worker threads through carefully crafted UDP message sequences, leading to a cascading failure where legitimate users cannot establish new connections or maintain existing sessions. The resource exhaustion affects not only the immediate SIP proxy functionality but also potentially impacts other services running within the same application server instance that rely on similar threading models. This vulnerability directly maps to CWE-400, which addresses "Uncontrolled Resource Consumption" and represents a classic denial of service scenario where system resources are consumed in an uncontrolled manner by malicious input.
The attack surface for CVE-2011-1316 aligns with ATT&CK technique T1499.004, which focuses on "Endpoint Denial of Service" through resource exhaustion attacks. This vulnerability demonstrates how attackers can leverage protocol-specific components to create system-wide availability issues rather than simply targeting specific application functions. The exploitation requires only remote access to send UDP messages to the targeted server, making it particularly dangerous as it can be executed from anywhere on the network without requiring physical access or authentication. The impact is particularly severe in environments where SIP services are critical for communication infrastructure, as the disruption can affect voice and video conferencing services, presence information, and other real-time communication features that depend on the SIP proxy functionality.
Organizations should implement immediate mitigations including updating to IBM WebSphere Application Server version 7.0.0.15 or later, which contains the necessary patches to address the worker thread exhaustion issue. Network-level controls such as UDP rate limiting and access control lists can provide additional defense-in-depth measures to limit the volume of UDP messages reaching the vulnerable components. System administrators should also monitor worker thread utilization and implement automated alerting for unusual resource consumption patterns that may indicate exploitation attempts. The vulnerability highlights the importance of proper resource management in application server components and underscores the need for robust input validation and rate limiting mechanisms in protocol handling components. Additionally, organizations should consider implementing network segmentation to isolate critical SIP services and reduce the potential impact of such attacks on overall system availability.