Denial of service in Cisco IOS/IOS XE

1) Denial of service

EUVDB-ID: #VU6162

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2017-3857

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to cause DoS conditions.

The vulnerability exists in the Layer 2 Tunneling Protocol (L2TP) parsing function due to insufficient validation of L2TP packets . An attacker can send a specially crafted L2TP packet and cause the affected device to reload.

Successful exploitation of the vulnerability results in denial of service on the vulnerable device.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Cisco IOS: 12.0 - 15.6.2 SP

CPE2.3

• cpe:2.3::::12.0:*:*:*:*:*:*:*
• cpe:2.3::::12.1:*:*:*:*:*:*:*
• cpe:2.3::::12.2.33:*:*:*:*:*:*:*
• cpe:2.3::::12.3:*:*:*:*:*:*:*
• cpe:2.3::::12.4:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios:15.0:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios:15.1:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios:15.2(5c)E:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios:15.3:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios:15.4:*:*:*:*:*:*:*

External links

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170322-l2tp

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.