CVE-2016-1333 in IOS
Summary
by MITRE
Cisco IOS 15.5(3)M and 15.6(1)T0a on Cisco 1000 Connected Grid routers allows remote authenticated users to cause a denial of service (device reload) via an SNMP request for unspecified BRIDGE MIB OIDs, aka Bug ID CSCux89878.
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Analysis
by VulDB Data Team • 07/08/2022
Cisco IOS routers running versions 15.5(3)M and 15.6(1)T0a are vulnerable to a remote authenticated denial of service condition that can be exploited by attackers with valid SNMP credentials. The vulnerability specifically manifests when the device receives SNMP requests targeting unspecified Bridge MIB OIDs within the BRIDGE MIB structure. This flaw falls under CWE-121 which represents stack-based buffer overflow conditions, though the specific implementation appears to involve improper handling of OID parsing rather than traditional buffer overflows. The vulnerability is tracked as Bug ID CSCux89878 and represents a significant operational risk for network infrastructure devices that rely on SNMP for monitoring and management purposes.
The technical execution of this vulnerability requires an attacker to possess valid SNMP credentials to authenticate to the affected Cisco 1000 Connected Grid router. Once authenticated, the attacker can send specially crafted SNMP requests that target Bridge MIB OIDs, which triggers an internal processing error within the IOS operating system. The device responds to these malformed requests by reloading its operating system, effectively causing a denial of service condition that disrupts network connectivity and services. This attack vector is particularly concerning because it can be executed remotely over the network, requiring only network access and valid authentication credentials rather than physical access or more sophisticated attack techniques. The vulnerability demonstrates a weakness in the SNMP subsystem's OID validation and processing mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption as it can compromise network availability and reliability for organizations relying on these routers for connected grid infrastructure. Network administrators may experience unexpected device reloads that can interrupt critical communications, particularly in environments where continuous network availability is paramount such as utility grid management systems, industrial control networks, or telecommunications infrastructure. The vulnerability can be exploited repeatedly by authenticated attackers, potentially leading to sustained denial of service conditions that may require manual intervention to restore normal operations. Organizations may also face compliance and security audit implications due to the unauthorized access capability that this vulnerability provides to authenticated attackers.
Mitigation strategies for this vulnerability should prioritize immediate software updates to address the specific IOS versions affected. Cisco released patches and updates to resolve this issue in subsequent IOS releases, making it essential for network administrators to apply these security updates as soon as possible. Network segmentation and access control measures can provide additional protection by limiting which entities can obtain valid SNMP credentials and access the affected routers. Implementing SNMPv3 instead of SNMPv1 or SNMPv2c can enhance authentication security and reduce the attack surface, though the vulnerability itself requires valid credentials to execute. Monitoring network traffic for unusual SNMP activity patterns and implementing intrusion detection systems can help identify exploitation attempts. The vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation, as it requires legitimate authentication credentials to be effective. Additionally, organizations should consider implementing network access controls to limit SNMP access to trusted management stations and establish regular patch management procedures to maintain device security posture against similar vulnerabilities.