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Check: GEN003603

SUSE Linux Enterprise Server v11 for System z STIG: GEN003603 (in versions v1 r12 through v1 r9)

Title

The system must not respond to Internet Control Message Protocol v4 (ICMPv4) echoes sent to a broadcast address. (Cat II impact)

Discussion

Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks.

Check Content

Verify the system does not respond to ICMP ECHO_REQUESTs set to broadcast addresses. Procedure: # cat /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts If the result is not 1, this is a finding.

Fix Text

Configure the system to not respond to ICMP ECHO_REQUESTs sent to broadcast addresses. Edit /etc/sysctl.conf and add a setting for "net.ipv4.icmp_echo_ignore_broadcasts=1" and reload the sysctls. Procedure: # echo "net.ipv4.icmp_echo_ignore_broadcasts=1" >> /etc/sysctl.conf # sysctl -p

Additional Identifiers

Rule ID: SV-45722r1_rule

Vulnerability ID: V-22410

Group Title: GEN003603

Expert Comments

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CCIs

CCIs tied to check.

Number	Definition
CCI-001551	The organization defines approved authorizations for controlling the flow of information between interconnected systems.

Controls

Controls tied to check. These are derived from the CCIs shown above.

Number	Title
AC-4	Information Flow Enforcement