TOSS must ignore IPv4 Internet Control Message Protocol (ICMP) redirect messages.
An XCCDF Rule
Description
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.
- ID
- SV-253118r991589_rule
- Version
- TOSS-04-040770
- Severity
- Medium
- References
- Updated
Remediation Templates
A Manual Procedure
Configure TOSS to ignore IPv4 ICMP redirect messages with the following command:
$ sudo sysctl -w net.ipv4.conf.all.accept_redirects=0
If "0" is not the system's default value then add or update the following line in the appropriate file under "/etc/sysctl.d":
net.ipv4.conf.all.accept_redirects = 0