CVE-2014-3261 in NX-OS
Summary
by MITRE
Buffer overflow in the Smart Call Home implementation in Cisco NX-OS on Fabric Interconnects in Cisco Unified Computing System 1.4 before 1.4(1i), NX-OS 5.0 before 5.0(3)U2(2) on Nexus 3000 devices, NX-OS 4.1 before 4.1(2)E1(1l) on Nexus 4000 devices, NX-OS 5.x before 5.1(3)N1(1) on Nexus 5000 devices, NX-OS 5.2 before 5.2(3a) on Nexus 7000 devices, and CG-OS CG4 before CG4(2) on Connected 1000 Connected Grid Routers allows remote SMTP servers to execute arbitrary code via a crafted reply, aka Bug IDs CSCtk00695, CSCts56633, CSCts56632, CSCts56628, CSCug14405, and CSCuf61322.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability described in CVE-2014-3261 represents a critical buffer overflow flaw within the Smart Call Home functionality of Cisco's networking and unified computing systems. This issue affects multiple product lines including Fabric Interconnects in Cisco Unified Computing System, various Nexus series switches, and Connected Grid Routers. The vulnerability specifically resides in the handling of SMTP responses within the Smart Call Home implementation, creating a pathway for remote code execution through crafted malicious replies from SMTP servers. The flaw stems from inadequate input validation and bounds checking when processing network communications, allowing attackers to overflow buffer structures and potentially gain unauthorized system access.
The technical implementation of this vulnerability involves the improper handling of network data within Cisco's NX-OS and CG-OS operating systems. When Smart Call Home functionality processes incoming SMTP responses, it fails to properly validate the length and content of received data before storing it in fixed-size buffers. This classic buffer overflow condition occurs because the system does not enforce strict bounds checking on the data being received from remote SMTP servers. The vulnerability manifests when a malicious SMTP server sends a specially crafted reply that exceeds the allocated buffer space, causing adjacent memory to be overwritten and potentially allowing an attacker to inject and execute arbitrary code with the privileges of the affected process. This type of vulnerability directly maps to CWE-121, which describes heap-based buffer overflow conditions, and aligns with ATT&CK technique T1059.007 for command and script injection.
The operational impact of this vulnerability extends across multiple Cisco product families and versions, creating widespread exposure for organizations utilizing these networking and computing platforms. Attackers could exploit this vulnerability remotely without authentication, making it particularly dangerous for systems connected to untrusted networks. The potential consequences include complete system compromise, data exfiltration, and disruption of network services. Organizations with affected Cisco Unified Computing System implementations, Nexus switches, and Connected Grid Routers face significant risk of unauthorized access and potential lateral movement within their network infrastructure. The vulnerability affects versions spanning multiple release cycles, indicating a persistent flaw in the codebase that required multiple patches across different product lines. This widespread impact aligns with ATT&CK tactic TA0006 (credential access) and TA0005 (defense evasion) as attackers could potentially establish persistent access and evade detection mechanisms.
Mitigation strategies for CVE-2014-3261 should prioritize immediate patch application to all affected Cisco products, with particular attention to the specific version ranges mentioned in the vulnerability description. Organizations must ensure that all Fabric Interconnects, Nexus 3000, 4000, 5000, and 7000 series switches, as well as Connected Grid Routers, receive the appropriate firmware updates. Network segmentation and access controls should be implemented to limit exposure of affected systems to untrusted SMTP servers, while monitoring systems should be configured to detect unusual SMTP traffic patterns that might indicate exploitation attempts. Cisco recommends disabling Smart Call Home functionality if it is not essential for operations, as this eliminates the attack surface entirely. Additionally, organizations should implement network-based intrusion detection systems with signatures specific to this vulnerability and conduct thorough vulnerability assessments to identify any systems that may not have received the necessary patches. The remediation process should include verification that all affected devices have been properly updated and that no legacy configurations remain that could expose the system to the vulnerability.