CVE-2016-3110 in JBoss Web Server
Summary
by MITRE
mod_cluster, as used in Red Hat JBoss Web Server 2.1, allows remote attackers to cause a denial of service (Apache http server crash) via an MCMP message containing a series of = (equals) characters after a legitimate element.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability identified as CVE-2016-3110 affects mod_cluster implementations within Red Hat JBoss Web Server 2.1, representing a critical denial of service weakness that can lead to complete Apache HTTP server crashes. This flaw specifically manifests when the system processes MCMP (Mod_cluster Management Protocol) messages containing sequences of equals characters following legitimate elements, creating a condition that triggers unexpected server behavior and eventual system failure.
The technical root cause of this vulnerability stems from inadequate input validation within the mod_cluster module's message parsing logic. When an attacker crafts a malicious MCMP message containing multiple consecutive equals characters after valid data elements, the parsing routine fails to properly handle this malformed input. This parsing failure creates a buffer over-read condition or memory corruption scenario that ultimately results in the Apache HTTP server process crashing. The vulnerability operates at the protocol level where MCMP messages are used for cluster management and load balancing operations, making it particularly dangerous in production environments where continuous availability is critical.
From an operational impact perspective, this vulnerability presents a significant risk to enterprise web infrastructure relying on mod_cluster for load balancing and cluster management. An unauthenticated remote attacker can exploit this weakness to cause repeated service disruptions, potentially leading to complete system outages that affect thousands of concurrent users. The DoS condition affects not just individual server instances but can cascade through entire cluster configurations, as the failure of one node often triggers failover mechanisms that may amplify the disruption. This vulnerability directly impacts the availability aspect of the CIA security triad and can be leveraged as part of broader attack campaigns targeting critical web infrastructure.
The vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and can be categorized under ATT&CK technique T1499.004 for network denial of service attacks. Organizations utilizing Red Hat JBoss Web Server 2.1 should implement immediate mitigations including applying the vendor-provided patches, configuring strict input validation rules for MCMP message processing, and implementing network-level restrictions that limit access to cluster management interfaces. Additional protective measures include deploying intrusion detection systems to monitor for suspicious MCMP traffic patterns and establishing robust monitoring protocols to detect early signs of exploitation attempts. The recommended approach combines both defensive measures and proactive patch management to ensure complete protection against this specific vulnerability while maintaining system availability and operational integrity.