CVE-2013-1122 in NX-OS
Summary
by MITRE
Cisco NX-OS on the Nexus 7000, when a certain Overlay Transport Virtualization (OTV) configuration is used, allows remote attackers to cause a denial of service (M1-Series module reload) via crafted packets, aka Bug ID CSCud15673.
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Analysis
by VulDB Data Team • 05/04/2019
The vulnerability identified as CVE-2013-1122 affects Cisco NX-OS operating system running on Nexus 7000 series switches with specific Overlay Transport Virtualization OTV configurations. This represents a critical denial of service weakness that can be exploited remotely by attackers to force reload of M1-Series modules, effectively disrupting network operations. The issue stems from improper handling of crafted packets within the OTV implementation, which creates a condition where legitimate network traffic can trigger system instability leading to complete module restarts. The vulnerability impacts organizations relying on OTV for overlay networking solutions, particularly those implementing data center interconnectivity using Cisco Nexus infrastructure.
The technical flaw manifests in the OTV packet processing logic where the system fails to properly validate incoming packet structures when the specific configuration parameters are active. This weakness allows attackers to construct packets with malformed or specially crafted fields that, when processed by the M1-Series module, trigger an exception handling routine that results in module reload. The vulnerability is classified under CWE-121 as a buffer overflow condition, though it specifically targets the module reload mechanism rather than direct memory corruption. The attack vector requires network access to the affected switch and can be executed without authentication, making it particularly dangerous in environments where network boundaries are not strictly enforced.
Operationally, this vulnerability poses significant risks to network availability and business continuity for organizations using Cisco Nexus 7000 switches in critical data center environments. When exploited, the M1-Series module reload causes temporary network disruption as the module reinitializes, potentially leading to service degradation or complete loss of connectivity for services relying on that specific module. The impact extends beyond immediate service interruption as the reload process may cause temporary loss of routing information and network state, requiring network convergence time and potentially affecting applications with strict availability requirements. Organizations utilizing OTV for interconnecting data centers face the highest risk as this vulnerability can be leveraged to disrupt critical inter-datacenter communications.
Mitigation strategies for CVE-2013-1122 should focus on immediate patch application from Cisco Security Advisory CSCud15673 which provides specific firmware updates addressing the OTV packet processing flaw. Network administrators should also implement traffic filtering mechanisms to block suspicious packets at network boundaries, particularly targeting the specific packet patterns that trigger the vulnerability. Configuration reviews should be conducted to identify and potentially disable OTV functionality when not required, reducing the attack surface. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service attacks, and organizations should consider implementing network monitoring solutions to detect anomalous packet patterns that may indicate exploitation attempts. Additionally, implementing proper network segmentation and access controls can limit the potential impact of successful exploitation attempts.