CVE-2021-1313 in IOS XR
Summary
by MITRE • 02/05/2021
Multiple vulnerabilities in the ingress packet processing function of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. For more information about these vulnerabilities, see the Details section of this advisory.
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Analysis
by VulDB Data Team • 02/24/2021
The vulnerability identified as CVE-2021-1313 affects Cisco IOS XR Software and represents a critical flaw in the ingress packet processing functionality that can be exploited by unauthenticated remote attackers. This vulnerability resides within the network operating system's packet handling mechanisms, specifically targeting how incoming network traffic is processed and validated. The affected software versions include various releases of Cisco IOS XR that are deployed on service provider routers and network infrastructure devices. These devices form the backbone of telecommunications networks and are responsible for routing traffic between different network segments, making them prime targets for attackers seeking to disrupt network services.
The technical nature of this vulnerability stems from insufficient validation of packet headers and processing routines within the ingress path of the network stack. When an attacker sends specially crafted packets to an affected device, the system fails to properly handle the malformed or unexpected packet structures during the ingress processing phase. This flaw can be categorized under CWE-129 Input Validation and CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization, as the packet processing functions do not adequately protect against race conditions or improper input handling during concurrent packet processing. The vulnerability manifests as a failure to properly validate packet attributes such as header lengths, sequence numbers, or protocol-specific fields that are essential for maintaining system stability.
The operational impact of CVE-2021-1313 is severe and directly translates to denial of service conditions that can render network infrastructure devices completely non-functional. An attacker can exploit this vulnerability to cause immediate system crashes, restarts, or memory exhaustion that results in complete service disruption for the affected network segments. The DoS condition affects not only the specific device but can cascade through network topology, potentially causing widespread disruption across interconnected networks that rely on the affected router for traffic forwarding. Network operators may experience extended downtime as they attempt to identify and remediate the affected systems, with the vulnerability potentially remaining undetected for extended periods due to its remote and unauthenticated nature.
Mitigation strategies for this vulnerability should include immediate implementation of Cisco's recommended security patches and software updates that address the ingress packet processing flaws. Network administrators should also implement ingress filtering mechanisms and access control lists to limit the types of packets that can reach vulnerable systems. The mitigation approach aligns with ATT&CK technique T1498.001 for Denial of Service and T1562.001 for Impairing Command and Control, as these methods help prevent exploitation while maintaining network functionality. Organizations should also implement network monitoring solutions that can detect anomalous packet patterns and unusual traffic behavior that may indicate exploitation attempts. Additionally, network segmentation strategies should be employed to limit the potential impact scope and ensure that even if one device is compromised, the entire network infrastructure remains operational. Regular security assessments and vulnerability scanning should be conducted to identify other potential weaknesses in the network infrastructure that may present similar attack vectors.