CVE-2012-4077 in NX-OS
Summary
by MITRE
Cisco NX-OS allows local users to gain privileges and execute arbitrary commands via the sed e option, aka Bug IDs CSCtf25457 and CSCtf27651.
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Analysis
by VulDB Data Team • 05/14/2017
The vulnerability identified as CVE-2012-4077 represents a critical privilege escalation flaw within Cisco NX-OS operating system versions. This issue affects network switches and routers running Cisco NX-OS software, specifically exposing a weakness in how the system handles command execution through the sed utility. The vulnerability enables local attackers with minimal system access to escalate their privileges and execute arbitrary commands, fundamentally compromising the device's security posture. The bug manifests through the sed e option, which is commonly used for text processing within Unix-like systems, but in this context creates an exploitable condition that bypasses normal access controls.
The technical implementation of this vulnerability stems from improper input validation within the NX-OS shell environment. When the sed command with the e option is processed, the system fails to properly sanitize user inputs, allowing malicious payloads to be interpreted and executed with elevated privileges. This flaw operates at the command-line interface level where legitimate administrative commands are processed, making it particularly dangerous as it can be exploited by attackers who have already gained access to a basic user account or through other initial compromise vectors. The sed e option specifically allows for command execution within the sed processing context, creating a path for arbitrary code injection that bypasses standard privilege boundaries. This type of vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-20, covering improper input validation.
The operational impact of CVE-2012-4077 extends beyond simple privilege escalation, as it provides attackers with complete control over affected network infrastructure. Once exploited, adversaries can manipulate network configurations, redirect traffic, install backdoors, or exfiltrate sensitive data from the compromised devices. This vulnerability directly affects network availability and integrity, potentially disrupting critical network services and creating persistent access points for further attacks. The impact is particularly severe in enterprise environments where Cisco switches serve as core network infrastructure components, as successful exploitation can lead to widespread network compromise and potential data breaches. From an attack perspective, this vulnerability maps to ATT&CK technique T1068, which covers local privilege escalation, and T1059, covering command and scripting interpreter, making it a significant concern for network security teams.
Mitigation strategies for CVE-2012-4077 require immediate implementation of Cisco's security patches and updates, as the vendor has released specific fixes addressing the sed command processing flaw. Network administrators should ensure all affected NX-OS devices receive the latest security updates and apply them through established change management processes. Additional protective measures include implementing strict access controls, disabling unnecessary command-line utilities, and monitoring system logs for suspicious command execution patterns. Security teams should also consider network segmentation and privilege separation to limit the potential impact if exploitation occurs. Regular vulnerability assessments and penetration testing should be conducted to identify similar issues within the network infrastructure. The remediation process must include thorough testing of patches in controlled environments before deployment to production systems to ensure operational stability and prevent service disruptions. Organizations should also implement comprehensive monitoring solutions to detect potential exploitation attempts and maintain detailed audit trails of all command executions on critical network devices.