Test case 11011
ICMP timestamp request, corresponding to CVE-1999-0524.
Vulnerability summary
ICMP information such as (1) netmask and (2) timestamp is allowed from arbitrary hosts.
What this test case checks
This test case probes a host for ICMP type 13 (Timestamp Request) responses. A response leaks the system clock, which can support time-skew correlation, session-prediction attacks against weak cryptographic protocols, and basic system fingerprinting. Many firewalls drop ICMP type 13 by default; some operating systems still respond.