CVE-2021-45445 in Clearpath MCP
Summary
by MITRE • 01/12/2022
Unisys ClearPath MCP TCP/IP Networking Services 59.1, 60.0, and 62.0 has an Infinite Loop.
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Analysis
by VulDB Data Team • 01/15/2022
The vulnerability identified as CVE-2021-45445 affects Unisys ClearPath MCP TCP/IP Networking Services versions 59.1, 60.0, and 62.0, representing a critical infinite loop condition that can lead to system instability and potential denial of service. This issue manifests within the networking stack of the ClearPath MCP operating system, which is designed for mainframe environments and supports enterprise-level applications. The infinite loop occurs during specific network protocol processing scenarios, particularly when handling certain TCP/IP packet structures or connection states. This flaw represents a significant security concern as it can be exploited by malicious actors to disrupt network services or cause system crashes, potentially affecting critical business operations that depend on continuous availability. The vulnerability is classified under CWE-835, which specifically addresses the infinite loop condition, and aligns with ATT&CK technique T1499.004 related to network disruption attacks. The affected ClearPath MCP environment operates within traditional enterprise mainframe infrastructures where network reliability is paramount for business continuity.
The technical implementation of this vulnerability stems from improper handling of network connection states or packet processing within the TCP/IP stack implementation. When specific network traffic patterns are processed by the affected networking services, the system enters a condition where a loop continues indefinitely without proper exit conditions. This typically occurs when the networking service fails to properly validate incoming packet structures or connection parameters, causing the protocol handler to repeatedly process the same data without advancing the state machine or terminating the processing cycle. The infinite loop consumes system resources continuously, leading to exhaustion of CPU cycles and potentially causing the entire networking service to become unresponsive. This behavior is particularly dangerous in mainframe environments where multiple concurrent connections and high-volume data processing are standard operations, making the impact of such a loop potentially catastrophic for system availability.
The operational impact of CVE-2021-45445 extends beyond simple denial of service conditions to potentially compromise entire network infrastructures within organizations utilizing ClearPath MCP systems. When the infinite loop occurs, it can cause cascading failures throughout the network stack, affecting not only the immediate service but also dependent applications and services that rely on TCP/IP connectivity. System administrators may observe gradual performance degradation followed by complete service unavailability as the loop consumes all available processing resources. The vulnerability affects organizations that depend on legacy mainframe systems for critical business functions, including financial services, government agencies, and large enterprises with extensive mainframe infrastructure. The impact is particularly severe in mission-critical environments where network availability is essential for business operations, as the vulnerability can lead to extended downtime and potential data processing interruptions. Organizations may experience difficulty in diagnosing the root cause due to the subtle nature of the loop condition, which might not immediately manifest as a clear system failure but rather as progressive performance degradation.
Organizations should implement immediate mitigation strategies including applying the vendor-provided patches and updates released for ClearPath MCP versions 59.1, 60.0, and 62.0. System administrators should also consider implementing network monitoring solutions that can detect anomalous resource consumption patterns or unusual connection behavior that might indicate the presence of the infinite loop condition. Network segmentation and access controls should be reviewed to limit potential attack vectors, while implementing proper intrusion detection systems that can identify suspicious network traffic patterns. Additionally, organizations should conduct thorough testing of the patched systems in controlled environments before deploying updates to production systems to ensure no regressions occur. The mitigation approach should also include regular monitoring of system logs and performance metrics to identify early signs of resource exhaustion or abnormal processing behavior. Organizations may need to implement temporary workarounds such as limiting specific types of network connections or implementing rate limiting to reduce the likelihood of triggering the vulnerable code paths. Compliance with industry standards such as those outlined in the NIST Cybersecurity Framework and ISO 27001 should be maintained throughout the remediation process to ensure comprehensive security coverage and proper documentation of the vulnerability resolution efforts.