TOSS must prevent IPv4 Internet Control Message Protocol (ICMP) redirect messages from being accepted.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-253130 | SRG-OS-000480-GPOS-00227 | TOSS-04-040890 | SV-253130r991589_rule | 2024-05-30 | 2 |
| 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. |
| ℹ️ Check |
|---|
| Verify TOSS will not accept IPv4 ICMP redirect messages. Note: If IPv4 is disabled on the system, this requirement is Not Applicable. Check the value of the default "accept_redirects" variables with the following command: $ sudo sysctl net.ipv4.conf.default.accept_redirects net.ipv4.conf.default.accept_redirects = 0 If the returned line does not have a value of "0", a line is not returned, or the line is commented out, this is a finding. |
| ✔️ Fix |
|---|
| Configure TOSS to prevent IPv4 ICMP redirect messages from being accepted with the following command: $ sudo sysctl -w net.ipv4.conf.default.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.default.accept_redirects=0 |