Finding ID | Version | Rule ID | IA Controls | Severity |
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V-215148 | UBTU-16-030550 | SV-215148r508033_rule | Medium |
Description |
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Responding to broadcast Internet Control Message Protocol (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks. |
STIG | Date |
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Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide | 2020-09-03 |
Check Text ( C-16347r285312_chk ) |
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Verify the Ubuntu operating system does not respond to IPv4 Internet Control Message Protocol (ICMP) echoes sent to a broadcast address. Check the value of the "icmp_echo_ignore_broadcasts" variable with the following command: # sudo sysctl net.ipv4.icmp_echo_ignore_broadcasts net.ipv4.icmp_echo_ignore_broadcasts=1 If the returned line does not have a value of "1", a line is not returned, or the retuned line is commented out, this is a finding. |
Fix Text (F-16345r285313_fix) |
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Configure the Ubuntu operating system to not respond to Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) echoes sent to a broadcast address with the following command: # sudo sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1 If "1" is not the system's default value then add or update the following line in "/etc/sysctl.conf" or in the appropriate file under "/etc/sysctl.d": net.ipv4.icmp_echo_ignore_broadcasts=1 |