CVE-2017-6740 : What You Need to Know

A number of vulnerabilities have been identified in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS versions 12.0 through 12.4 and 15.0 through 15.6, as well as IOS XE versions 2.2 through 3.17. These vulnerabilities could permit an authenticated attacker to execute code remotely on an impacted system or cause the system to restart. Exploiting these vulnerabilities entails sending a specially crafted SNMP packet to the affected system via either IPv4 or IPv6. It should be noted that only traffic directed towards the affected system can be leveraged to exploit these vulnerabilities. The vulnerabilities are attributed to a buffer overflow issue in the SNMP subsystem of the affected software. All iterations of SNMP, including Versions 1, 2c, and 3, are impacted by these vulnerabilities. To exploit the vulnerabilities using SNMP Version 2c or earlier, the attacker must be aware of the SNMP read-only community string of the targeted system. For exploiting the vulnerabilities via SNMP Version 3, the attacker must possess user credentials for the impacted system. It is important to consider all devices that have enabled SNMP and have not explicitly excluded the affected Management Information Bases (MIBs) or Object Identifiers (OIDs) as potentially vulnerable. These vulnerabilities are tracked under the Cisco Bug IDs: CSCve66601.

Understanding CVE-2017-6740

This CVE identifies multiple vulnerabilities in the SNMP subsystem of Cisco IOS and IOS XE, allowing remote code execution and system reload.

What is CVE-2017-6740?

The CVE-2017-6740 vulnerability involves buffer overflow issues in the SNMP subsystem of Cisco IOS versions 12.0 through 12.4 and 15.0 through 15.6, as well as IOS XE versions 2.2 through 3.17.

The Impact of CVE-2017-6740

Authenticated attackers can remotely execute code or cause system restarts on affected systems.
Exploitation requires sending crafted SNMP packets via IPv4 or IPv6.
Only traffic directed at affected systems can be used for exploitation.
All SNMP versions (1, 2c, 3) are vulnerable.

Technical Details of CVE-2017-6740

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerabilities stem from buffer overflow in the SNMP subsystem of affected Cisco software.

Affected Systems and Versions

Cisco IOS versions 12.0 through 12.4 and 15.0 through 15.6
IOS XE versions 2.2 through 3.17

Exploitation Mechanism

Attackers exploit the vulnerabilities by sending specially crafted SNMP packets.
SNMP Versions 1, 2c, and 3 are all susceptible.

Mitigation and Prevention

Protecting systems from CVE-2017-6740 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply patches provided by Cisco to address the vulnerabilities.
Disable SNMP if not essential for operations.
Implement firewall rules to restrict SNMP traffic.

Long-Term Security Practices

Regularly update and patch systems to prevent known vulnerabilities.
Monitor network traffic for any suspicious SNMP activities.

Patching and Updates

Stay informed about security advisories from Cisco.
Apply updates promptly to mitigate potential risks.