Finding ID | Version | Rule ID | IA Controls | Severity |
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V-235019 | SLES-15-040340 | SV-235019r622137_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 modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack. |
STIG | Date |
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SUSE Linux Enterprise Server 15 Security Technical Implementation Guide | 2021-03-04 |
Check Text ( C-38207r619326_chk ) |
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Verify the SUSE operating system does not accept IPv4 ICMP redirect messages by default. Check the value of the default IPv4 accept_redirects variable with the following command: > sudo sysctl net.ipv4.conf.default.accept_redirects net.ipv4.conf.default.accept_redirects = 0 If the network parameter "ipv4.conf.default.accept_redirects" is not equal to "0" or nothing is returned, this is a finding. |
Fix Text (F-38170r619327_fix) |
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Configure the SUSE operating system to not accept IPv4 ICMP redirect messages by default by running the following command as an administrator: > sudo sysctl -w net.ipv4.conf.default.accept_redirects=0 If "0" is not the system's default value, add or update the following line in "/etc/sysctl.d/99-stig.conf": > sudo sh -c 'echo "net.ipv4.conf.default.accept_redirects=0" >> /etc/sysctl.d/99-stig.conf' > sudo sysctl --system |