CVE-2017-6744 in IOS
Summary
by MITRE
The Simple Network Management Protocol (SNMP) subsystem of Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 2.2 through 3.17 contains multiple vulnerabilities that could allow an authenticated, remote attacker to remotely execute code on an affected system or cause an affected system to reload. An attacker could exploit these vulnerabilities by sending a crafted SNMP packet to an affected system via IPv4 or IPv6. Only traffic directed to an affected system can be used to exploit these vulnerabilities. The vulnerabilities are due to a buffer overflow condition in the SNMP subsystem of the affected software. The vulnerabilities affect all versions of SNMP: Versions 1, 2c, and 3. To exploit these vulnerabilities via SNMP Version 2c or earlier, the attacker must know the SNMP read-only community string for the affected system. To exploit these vulnerabilities via SNMP Version 3, the attacker must have user credentials for the affected system. All devices that have enabled SNMP and have not explicitly excluded the affected MIBs or OIDs should be considered vulnerable. Cisco Bug IDs: CSCve78027, CSCve60276.
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Analysis
by VulDB Data Team • 09/09/2024
The vulnerability identified as CVE-2017-6744 represents a critical buffer overflow condition within the Simple Network Management Protocol subsystem of Cisco IOS and IOS XE operating systems. This flaw affects a broad range of Cisco network infrastructure devices including routers and switches running versions 12.0 through 12.4 and 15.0 through 15.6 of IOS, along with IOS XE versions 2.2 through 3.17. The vulnerability stems from inadequate input validation within the SNMP processing logic, creating a condition where maliciously crafted SNMP packets can trigger memory corruption that leads to arbitrary code execution or system reloads. The attack vector requires network access to the target device through either IPv4 or IPv6 protocols, making it particularly dangerous for devices with exposed SNMP services on public networks.
The technical exploitation of this vulnerability follows established patterns that align with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw affects all three versions of SNMP protocol - Version 1, 2c, and 3 - though the attack requirements differ based on the version used. For SNMP Version 2c and earlier, attackers must possess the read-only community string to successfully exploit the vulnerability, while SNMP Version 3 requires valid user credentials including authentication and privacy parameters. This differential attack complexity reflects the varying security models implemented across different SNMP versions, yet all remain equally susceptible to the underlying buffer overflow condition. The vulnerability specifically impacts MIBs and OIDs that are enabled on the affected systems, meaning any device with SNMP enabled and without explicit exclusion of vulnerable management information bases should be considered at risk.
The operational impact of CVE-2017-6744 extends beyond simple system disruption to encompass full compromise of affected network devices. An authenticated remote attacker with the appropriate credentials can leverage this vulnerability to execute arbitrary code on the target system, potentially gaining administrative privileges and establishing persistent access to the network infrastructure. The ability to cause system reloads represents a denial-of-service capability that could disrupt network operations, while the code execution potential allows for complete system compromise. This vulnerability directly maps to ATT&CK technique T1068, which describes the use of local or remote code execution to gain unauthorized access to systems. The implications are particularly severe for enterprise networks where routers and switches form the backbone of network connectivity, as compromise of these devices can enable attackers to redirect traffic, perform man-in-the-middle attacks, or establish lateral movement within the network infrastructure.
Mitigation strategies for CVE-2017-6744 should encompass multiple defensive layers to protect against exploitation attempts. Organizations must first implement proper SNMP access controls by disabling SNMPv1 and SNMPv2c where possible, favoring the more secure SNMPv3 implementation with strong authentication and encryption. Network segmentation should be employed to limit access to SNMP services, ensuring that only authorized management systems can communicate with network devices. Regular patching and upgrading of affected IOS and IOS XE versions is essential, with Cisco releasing specific fixes for this vulnerability under bug IDs CSCve78027 and CSCve60276. Network monitoring should include detection of anomalous SNMP traffic patterns that might indicate exploitation attempts, while firewall rules should restrict SNMP access to known management stations only. Additionally, implementing SNMP MIB and OID access controls to limit what information can be retrieved helps reduce the attack surface, and regular security audits should verify that SNMP services are properly configured and that vulnerable versions have been updated. The vulnerability demonstrates the critical importance of maintaining current firmware versions and following security best practices for network infrastructure management.