7.1.2 Disable Send Packet Redirects - 'net.ipv4.conf.default.send_redirects = 0'

Information

ICMP Redirects are used to send routing information to other hosts. As a host itself does
not act as a router (in a host only configuration), there is no need to send redirects.

*Rationale*

An attacker could use a compromised host to send invalid ICMP redirects to other router
devices in an attempt to corrupt routing and have users access a system set up by the
attacker as opposed to a valid system.

Solution

Set the net.ipv4.conf.all.send_redirects and
net.ipv4.conf.default.send_redirects parameters to 0 in /etc/sysctl.conf-net.ipv4.conf.all.send_redirects=0
net.ipv4.conf.default.send_redirects=0

Modify active kernel parameters to match-
# /sbin/sysctl -w net.ipv4.conf.all.send_redirects=0
# /sbin/sysctl -w net.ipv4.conf.default.send_redirects=0
# /sbin/sysctl -w net.ipv4.route.flush=1

See Also

https://workbench.cisecurity.org/files/91

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(12), CSCv6|9.2

Plugin: Unix

Control ID: 9e3078247e961b2fb5e9c73aae04c491ca6fc36095237e6bdd3c6f4732e43c77