Vulnerability identifier: #VU11362

Vulnerability risk: Medium

CVSSv3.1: 8.2 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2018-0173

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Cisco IOS XE
Operating systems & Components / Operating system

Vendor: Cisco Systems, Inc

Description
The vulnerability allows a remote unauthenticated attacker to cause DoS condition on the target system.

The weakness exists in the function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets due to incomplete input validation of encapsulated option 82 information that it receives in DHCPOFFER messages from DHCPv4 servers. A remote attacker can send a specially crafted DHCPv4 packet and cause the service to crash.

Mitigation
Update to evrsions 16.6(2.67), 16.5(1.321), 16.3(5.73), 15.6(2.18)SP3, 15.6(2)SP4, 15.5(3)S6.23, 15.4(3)S9, 15.2(6.5.1i)E1, 15.2(6.4.66i)E1, 15.2(6.4.63i)E1, 15.2(6)E1, 15.2(4.7.6)EA7, 15.0(1.9.1)SQD8 or 12.2(60)EZ13.

Vulnerable software versions

Cisco IOS XE: 16.3.4

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2

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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?

Yes. This vulnerability is being exploited in the wild.