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TCP timestamps RRS feed

  • Question

  • I use Openvas to scan the Windows server 2012R2

    and get vulnerability, TCP Timestamps

    Summary
    The remote host implements TCP timestamps and therefore allows to compute the uptime.
    Vulnerability Detection Result
    It was detected that the host implements RFC1323.

    The following timestamps were retrieved with a delay of 1 seconds in-between:
    Packet 1: 1487459
    Packet 2: 1487560
    Impact
    A side effect of this feature is that the uptime of the remote host can sometimes be computed.
    Solution
    Solution type:   Mitigation
    To disable TCP timestamps on linux add the line 'net.ipv4.tcp_timestamps = 0' to /etc/sysctl.conf. Execute 'sysctl -p' to apply the settings at runtime.
    To disable TCP timestamps on Windows execute 'netsh int tcp set global timestamps=disabled'
    Starting with Windows Server 2008 and Vista, the timestamp can not be completely disabled.
    The default behavior of the TCP/IP stack on this Systems is to not use the Timestamp options when initiating TCP connections, but use them if the TCP peer that is initiating communication includes them in their synchronize (SYN) segment.
    See also: http://www.microsoft.com/en-us/download/details.aspx?id=9152
    Affected Software/OS
    TCP/IPv4 implementations that implement RFC1323.
    Vulnerability Insight
    The remote host implements TCP timestamps, as defined by RFC1323.
    Vulnerability Detection Method
    Special IP packets are forged and sent with a little delay in between to the target IP. The responses are searched for a timestamps. If found, the timestamps are reported.
    Details: TCP timestamps (OID: 1.3.6.1.4.1.25623.1.0.80091)
    Version used: $Revision: 10411 $
    References
    Other:    http://www.ietf.org/rfc/rfc1323.txt

    I have tested the method below
    To disable TCP timestamps on Windows execute 'netsh int tcp set global timestamps=disabled'

    But it does NOT work,
    Since it stated "Starting with Windows Server 2008 and Vista, the timestamp can not be completely disabled."
    Also, I have searched in the Internet, it seems that Windows 2012 cannot disable the timestamp

    Is it true, or
    Is it anyway to disable the timestamp?

    Thx a lot


    Wednesday, July 25, 2018 2:25 AM

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