CVE-2019-4720 in WebSphere Application Server
Summary
by MITRE
IBM WebSphere Application Server 7.0, 8.0, 8.5, and 9.0 is vulnerable to a denial of service, caused by sending a specially-crafted request. A remote attacker could exploit this vulnerability to cause the server to consume all available memory. IBM X-Force ID: 172125.
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Analysis
by VulDB Data Team • 03/27/2024
IBM WebSphere Application Server versions 7.0, 8.0, 8.5, and 9.0 contain a critical denial of service vulnerability that stems from insufficient input validation in the server's request processing mechanism. This vulnerability manifests when the application server receives a malformed HTTP request that triggers an improper memory allocation behavior within the server's processing pipeline. The flaw exists in the server's handling of specific request parameters that are not adequately sanitized or constrained before being processed by the underlying memory management system. Attackers can exploit this weakness by crafting malicious requests that cause the server to continuously allocate memory without proper cleanup, leading to gradual memory exhaustion and eventual system unresponsiveness. The vulnerability falls under the CWE-400 category of Uncontrolled Resource Consumption, specifically targeting memory allocation patterns within web application servers. From an operational perspective, this vulnerability represents a significant risk to enterprise environments where WebSphere servers handle critical business applications, as it can be exploited remotely without requiring authentication credentials. The attack vector allows malicious actors to consume all available system memory through a single or series of crafted requests, effectively rendering the application server unavailable to legitimate users. This type of attack aligns with ATT&CK technique T1499.004 for Network Denial of Service, where adversaries target application layer resources to disrupt service availability. The impact extends beyond simple service interruption as the memory exhaustion can potentially cause cascading failures in dependent systems and services that rely on the affected WebSphere instances.
The technical exploitation of this vulnerability demonstrates a classic resource exhaustion attack pattern where the malicious request triggers an infinite or near-infinite loop in the server's memory allocation logic. When the server processes the specially crafted request, it fails to properly validate the request parameters and instead proceeds to allocate memory blocks in a manner that grows without bounds. This behavior is particularly dangerous because it can occur silently in production environments, making detection difficult until the system becomes completely unresponsive. The vulnerability's persistence across multiple major versions of WebSphere indicates a fundamental flaw in the request handling architecture that was not properly addressed through the version upgrade process. Organizations running these affected versions face a critical security risk as the exploitation can be performed entirely from external networks without requiring any prior access or credentials. The memory consumption pattern suggests that the vulnerability may be related to improper handling of HTTP headers or request body content that triggers recursive processing or buffer allocation behaviors.
Organizations should implement immediate mitigations including network-level protections such as firewalls and intrusion prevention systems that can detect and block suspicious request patterns targeting the WebSphere server. The most effective short-term solution involves applying the relevant security patches provided by IBM as soon as possible, which typically address the input validation deficiencies in the request processing pipeline. Additionally, implementing rate limiting and request size restrictions at the network perimeter can help reduce the impact of exploitation attempts. Monitoring systems should be configured to alert on unusual memory consumption patterns or repeated connection attempts from single sources. From a defensive standpoint, organizations should consider implementing application firewalls that can inspect HTTP traffic for malicious patterns and block requests that match known exploit signatures. The vulnerability's classification as a denial of service issue means that traditional security controls like antivirus software or endpoint protection may not be sufficient to prevent exploitation. Long-term mitigation strategies should include regular security assessments of application server configurations and comprehensive patch management processes that ensure all supported versions remain up to date with security fixes. Organizations should also consider implementing redundant systems or load balancing configurations that can automatically failover when a primary server becomes unresponsive due to memory exhaustion attacks. The ATT&CK framework suggests that this vulnerability could be part of a broader attack chain where initial access leads to privilege escalation through memory-based attacks that ultimately result in service disruption.