Finding ID | Version | Rule ID | IA Controls | Severity |
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V-221880 | OL07-00-040650 | SV-221880r880657_rule | Medium |
Description |
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ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table, possibly revealing portions of the network topology. |
STIG | Date |
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Oracle Linux 7 Security Technical Implementation Guide | 2023-06-02 |
Check Text ( C-23595r880655_chk ) |
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Verify the system does not allow interfaces to perform IPv4 ICMP redirects by default. # grep -r net.ipv4.conf.default.send_redirects /run/sysctl.d/* /etc/sysctl.d/* /usr/local/lib/sysctl.d/* /usr/lib/sysctl.d/* /lib/sysctl.d/* /etc/sysctl.conf 2> /dev/null If "net.ipv4.conf.default.send_redirects" is not configured in the "/etc/sysctl.conf" file or in any of the other sysctl.d directories, is commented out or does not have a value of "0", this is a finding. Check that the operating system implements the "default send_redirects" variables with the following command: # /sbin/sysctl -a | grep net.ipv4.conf.default.send_redirects net.ipv4.conf.default.send_redirects = 0 If the returned line does not have a value of "0", this is a finding. If conflicting results are returned, this is a finding. |
Fix Text (F-23584r880656_fix) |
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Configure the system not to allow interfaces to perform IPv4 ICMP redirects by default. Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a configuration file in the /etc/sysctl.d/ directory (or modify the line to have the required value): net.ipv4.conf.default.send_redirects = 0 Issue the following command to make the changes take effect: # sysctl --system |