CVE-2017-6739: Cisco IOS and IOS XE Software SNMP Remote Code Execution Vulnerability
A vulnerability in the SNMP implementation of could allow an authenticated, remote attacker to cause a reload of the affected system or to remotely execute code. An attacker could exploit this vulnerability by sending a crafted SNMP packet to the affected device. The vulnerability is due to a buffer overflow in the affected code area. The vulnerability affects all versions of SNMP (versions 1, 2c, and 3). The attacker must know the SNMP read only community string (SNMP version 2c or earlier) or the user credentials (SNMPv3). An exploit could allow the attacker to execute arbitrary code and obtain full control of the system or to cause a reload of the affected system. Only traffic directed to the affected system can be used to exploit this vulnerability.
Other sources
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: CSCve66540.
The Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE contains a vulnerability that could allow an authenticated, remote attacker to remotely execute code on an affected system or cause an affected system to reload.
— CISA
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Explicitly configure the device SNMP agent to exclude the affected MIBs and OIDs from SNMP responses/queries (i.e., add the affected MIBs/OIDs to the SNMP exclusion list on the device).
SNMP excluded_MIBs/OIDs = exclude affected MIBs/OIDs - Compensating control
Restrict SNMP access to the device to trusted management hosts only by applying ACLs or firewall rules for IPv4 and IPv6 so that only authorized source IPs can send SNMP packets to the device.
- Operational
Rotate SNMP credentials: change the SNMP read-only community string (for SNMP v1/v2c) and change/remove or reset SNMPv3 user credentials to new, strong credentials.
Event History
Frequently Asked Questions
What is the severity of CVE-2017-6739?
CVE-2017-6739 is rated as high severity, as it allows remote code execution on affected Cisco IOS and IOS XE systems.
How do I fix CVE-2017-6739?
To fix CVE-2017-6739, upgrade the affected Cisco IOS or IOS XE version to the latest update provided by Cisco.
Which Cisco products are affected by CVE-2017-6739?
CVE-2017-6739 affects various versions of Cisco IOS from 12.0 to 12.4 and 15.0 to 15.6, as well as IOS XE versions from 2.2 to 3.17.
Can CVE-2017-6739 be exploited remotely?
Yes, CVE-2017-6739 can be exploited remotely by an authenticated attacker to execute arbitrary code on the affected device.
What types of attacks can be executed using CVE-2017-6739?
CVE-2017-6739 allows attackers to gain control over the device, potentially leading to unauthorized access and network disruptions.