CVE-2022-20845 in IOS XR
Summary
by MITRE • 11/15/2024
A vulnerability in the TL1 function of Cisco Network Convergence System (NCS) 4000 Series could allow an authenticated, local attacker to cause a memory leak in the TL1 process. This vulnerability is due to TL1 not freeing memory under some conditions. An attacker could exploit this vulnerability by connecting to the device and issuing TL1 commands after being authenticated. A successful exploit could allow the attacker to cause the TL1 process to consume large amounts of memory. When the memory reaches a threshold, the Resource Monitor (Resmon) process will begin to restart or shutdown the top five consumers of memory, resulting in a denial of service (DoS).Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.This advisory is part of the September 2022 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see .
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Analysis
by VulDB Data Team • 11/15/2024
The vulnerability identified as CVE-2022-20845 affects the TL1 function within Cisco Network Convergence System NCS 4000 Series devices, representing a significant security concern for network infrastructure deployments. This flaw exists within the telecommunications equipment that serves as critical infrastructure for service providers and enterprises, making its exploitation particularly concerning from both operational and security perspectives. The vulnerability specifically targets the TL1 (Telecommunications Local Interface) protocol implementation which is used for managing and controlling telecommunications equipment through standardized command structures.
The technical root cause of this vulnerability stems from improper memory management within the TL1 process implementation. According to CWE-401, this represents a classic memory leak condition where allocated memory is not properly released back to the system under certain operational conditions. The flaw manifests when authenticated users connect to the device and execute TL1 commands, creating a scenario where memory allocation occurs without corresponding deallocation. This memory leak progressively consumes available system resources, eventually reaching critical thresholds that trigger system-level protective mechanisms.
The operational impact of this vulnerability extends beyond simple resource exhaustion, creating a potential denial of service condition that can severely disrupt network operations. When memory consumption reaches predetermined thresholds, the Resource Monitor (Resmon) process automatically intervenes by restarting or shutting down the top memory-consuming processes, including the critical TL1 process itself. This automatic intervention creates a cascading failure effect that can render the device unable to process legitimate TL1 commands, effectively disabling the telecommunications management functions. The vulnerability's local nature means that only authenticated users with access to the device can exploit it, but this requirement does not mitigate the severity given that authorized personnel may be compromised or that the vulnerability could be exploited through lateral movement within a network.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion. The attack vector requires authentication, making it a privilege escalation scenario rather than a simple external exploitation attempt, though the implications remain severe for network availability. The vulnerability's classification as a memory leak in telecommunications management protocols demonstrates the increasing complexity of modern network infrastructure security challenges. Organizations deploying Cisco NCS 4000 Series equipment must understand that this vulnerability affects core operational functions that support service delivery and network management, making it a critical security concern for network reliability and business continuity.
Cisco has addressed this vulnerability through targeted software updates released as part of their September 2022 IOS XR Software Security Advisory Bundled Publication, emphasizing the importance of timely patch management for network infrastructure. The absence of workaround solutions highlights the fundamental nature of the memory management flaw, requiring complete software remediation rather than temporary mitigations. Network administrators should prioritize immediate deployment of these updates across affected systems, particularly in environments where network availability is critical for service delivery operations and where the TL1 interface is actively used for device management and monitoring functions.