CVE-2017-6737 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: CSCve60402.
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Analysis
by VulDB Data Team • 07/31/2025
The vulnerability identified as CVE-2017-6737 represents a critical buffer overflow condition within the Simple Network Management Protocol subsystem of Cisco IOS and IOS XE software versions spanning from 12.0 through 12.4 and 15.0 through 15.6. This flaw exists in the SNMP processing logic where insufficient input validation allows maliciously crafted SNMP packets to trigger memory corruption. The vulnerability affects all SNMP versions including v1, v2c, and v3, making it particularly concerning given the widespread deployment of SNMP for network monitoring and management purposes. The buffer overflow occurs when the SNMP subsystem processes incoming packets without adequate bounds checking, potentially leading to arbitrary code execution or system crashes. This vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and specifically relates to the improper handling of input data within network protocol implementations. The attack vector requires an authenticated remote attacker with network access to the targeted system, meaning that the vulnerability cannot be exploited from outside the network perimeter without proper credentials.
The operational impact of CVE-2017-6737 extends beyond simple system availability issues to potentially enable full system compromise through remote code execution. When exploited successfully, the buffer overflow can allow an attacker to execute arbitrary code with the privileges of the affected system, potentially leading to complete network compromise. The vulnerability's exploitation requires specific conditions based on SNMP version being used, with SNMP v2c and earlier requiring knowledge of the read-only community string, while SNMP v3 requires valid user credentials. This credential requirement does not eliminate the threat, as network administrators often use default or weak credentials that can be easily compromised through various attack techniques. The fact that all affected versions of SNMP are vulnerable regardless of the specific SNMP version used means that organizations cannot simply disable certain SNMP versions to mitigate the risk. The attack requires only that the targeted system has SNMP enabled and has not explicitly excluded the affected MIBs or OIDs, making the vulnerability pervasive across network infrastructure that utilizes SNMP for monitoring purposes.
Cisco's identification of this vulnerability through Bug ID CSCve60402 highlights the severity of the issue within their own product ecosystem. The mitigation strategies typically involve applying the latest security patches and updates from Cisco, which address the buffer overflow conditions in the SNMP processing code. Network administrators should implement the principle of least privilege by disabling SNMP on devices where it is not required, and where SNMP is necessary, ensure that only authorized network segments can communicate with SNMP-enabled devices. The vulnerability's characteristics align with ATT&CK technique T1078 which covers Valid Accounts and T1210 which covers Exploitation of Remote Services, demonstrating how this vulnerability can be leveraged as part of broader attack campaigns targeting network infrastructure. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of exploitation, particularly focusing on SNMP traffic between network segments. The vulnerability's presence in both legacy IOS versions and newer IOS XE releases indicates that comprehensive patch management and upgrade strategies are essential for maintaining network security posture, as the affected software versions span multiple generations of Cisco's network operating system.
The broader implications of CVE-2017-6737 extend to enterprise network security frameworks, as SNMP is widely deployed across network infrastructure for monitoring, configuration management, and performance tracking. The vulnerability demonstrates the critical importance of input validation in network protocol implementations, as even seemingly benign management protocols can become attack vectors when proper bounds checking is not implemented. Organizations should conduct comprehensive vulnerability assessments to identify all devices running affected SNMP versions, particularly focusing on network devices such as routers, switches, and firewalls that typically have SNMP enabled by default. The remediation process requires careful planning due to the potential for service disruption during patch application, and organizations should establish rollback procedures in case patch installation causes unexpected issues. Additionally, monitoring for unusual SNMP traffic patterns and implementing intrusion detection systems that can identify potential exploitation attempts will help in early detection of attacks targeting this vulnerability. The vulnerability serves as a reminder of the critical need for continuous security monitoring and the importance of maintaining up-to-date security patches across all network infrastructure components.