CVE-2020-4869 in MQ Appliance
Summary
by MITRE • 01/12/2021
IBM MQ Appliance 9.2 CD and 9.2 LTS is vulnerable to a denial of service, caused by a buffer overflow. A remote attacker could send a specially crafted SNMP query to cause the appliance to reload. IBM X-Force ID: 190831.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 02/11/2021
The vulnerability identified as CVE-2020-4869 affects IBM MQ Appliance versions 9.2 CD and 9.2 LTS, representing a critical buffer overflow flaw that can be exploited remotely to trigger a denial of service condition. This vulnerability specifically manifests within the appliance's handling of Simple Network Management Protocol queries, which are commonly used for system monitoring and management purposes. The flaw exists in the SNMP processing functionality where insufficient input validation allows an attacker to craft malicious queries that exceed allocated buffer boundaries, leading to unexpected system behavior and potential service interruption.
The technical implementation of this vulnerability stems from inadequate bounds checking within the SNMP query parser component of the IBM MQ Appliance. When a remote attacker submits a specially crafted SNMP query containing oversized or malformed data, the system fails to properly validate the input length against allocated buffer space. This buffer overflow condition causes the appliance to crash and subsequently reloads automatically, effectively disrupting the messaging services that rely on the appliance for message queuing and transport. The vulnerability operates at the network level, requiring only basic network connectivity to the appliance's SNMP port, making it particularly dangerous as it can be exploited from external networks without requiring authentication credentials.
From an operational impact perspective, this vulnerability creates significant business disruption risks for organizations relying on IBM MQ Appliance for critical messaging infrastructure. The automatic reload mechanism effectively constitutes a denial of service attack that can interrupt message processing, potentially causing data loss, application downtime, and service degradation across dependent systems. The vulnerability's remote exploitability means that attackers can target the appliance from anywhere on the network, eliminating the need for physical access or local network presence. This makes it particularly attractive to threat actors seeking to disrupt operations or create cover for other malicious activities. The impact extends beyond simple service interruption as the appliance may lose configuration settings or pending messages during the reload process, leading to potential data integrity issues.
Organizations should implement immediate mitigations including network segmentation to restrict access to the appliance's SNMP ports, deployment of network access control lists to limit who can reach the appliance, and application of the vendor-provided security patches. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1499.004 for network denial of service attacks. System administrators should also consider implementing monitoring solutions to detect unusual SNMP traffic patterns and establish incident response procedures for handling appliance reload events. Regular vulnerability assessments and security audits should be conducted to identify similar buffer overflow conditions in other network services and ensure comprehensive protection against similar threats. The remediation process requires careful planning to minimize service disruption during patch deployment while maintaining operational continuity for mission-critical messaging services.