CVE-2017-6743
KEVmassAuthenticated SNMP Buffer Overflow RCE in Cisco IOS and IOS XE
CISA: Cisco IOS and IOS XE Software SNMP Remote Code Execution Vulnerability
CVE-2017-6743 is a buffer overflow (CWE-119) in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE that allows an authenticated, remote attacker to execute arbitrary code with full system control or force an affected device to reload. Exploitation requires sending a crafted SNMP packet (over IPv4 or IPv6) directly to the affected device; for SNMPv1/v2c the attacker must know the read-only community string, and for SNMPv3 the attacker must hold valid user credentials, so only devices with SNMP enabled are at risk. All SNMP versions (1, 2c, and 3) are affected, and any device with SNMP enabled that has not explicitly excluded the affected MIBs/OIDs should be considered vulnerable. The flaw affects Cisco IOS and IOS XE across Cisco's enormous installed base of enterprise routers and switches. The vulnerability was added to CISA's Known Exploited Vulnerabilities catalog on 2022-03-03, indicating confirmed exploitation in the wild, and EPSS assigns a 10.7% probability of exploitation within 30 days (96th percentile).
What to do: Inventory all IOS/IOS XE devices and determine which have SNMP enabled with the affected MIBs/OIDs, then upgrade to fixed releases identified via the Cisco IOS Software Checker (per the KEV required action of applying vendor updates). As an interim mitigation, restrict SNMP access with interface/access-control lists, disable SNMP where unused, or exclude the affected MIBs/OIDs as described in the Cisco advisory workarounds; rotate SNMP community strings and v3 credentials is also prudent since exploitability depends on knowing them.
| Cisco IOS | All releases with SNMP enabled and affected MIBs/OIDs not explicitly excluded (SNMP v1, 2c, and 3 affected); check the Cisco IOS Software Checker for fixed rele |
| Cisco IOS XE | All releases with SNMP enabled and affected MIBs/OIDs not explicitly excluded (SNMP v1, 2c, and 3 affected); check the Cisco IOS Software Checker for fixed rele |
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
The Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE Software 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. A successful exploit could allow the attacker to execute arbitrary code and obtain full control of the affected system or cause the affected system to reload. Customers are advised to apply the workaround as contained in the Workarounds section below. Fixed software information is available via the Cisco IOS Software Checker. All devices that have enabled SNMP and have not explicitly excluded the affected MIBs or OIDs should be considered vulnerable. There are workarounds that address these vulnerabilities.
- Affected
- Cisco IOS and IOS XE Software
- Required action
- Apply updates per vendor instructions.
- Due date
- Ransomware use
- Unknown
- Vendors
- cisco
- Products
- ios, ios xe
- Weakness
- CWE-119
- Vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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