Re: Weak TCP Sequence Numbers in Sonicwall SOHO Firewall

From: John Duksta (jdukstaat_private)
Date: Thu Jul 26 2001 - 09:24:39 PDT

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    Dan,
    
    Did you run this scan against the internal or external interface
    of the SonicWall? Every scan I've ever run against a SonicWall
    from the outside exhibited the OS Characteristics of the OS
    actually running services port forwarded behind it.
    
    e.g. a friend with a SonicWall was running his web and mail
    servers behind a Sonicwall on an AIX box. When we nmap scanned
    the external interface of the Sonicwall, it showed up as an
    AIX box.
    
    -john
    
    At 05:17 PM 7/25/2001 -0600, Dan Ferris wrote:
    >This may not seem bad, but to me it seems that this defeats the point of NAT
    >if somebody can steal your sessions.  Note the section on TCP sequence
    >prediction.  This was a Sonicwall SOHO firewall.
    >
    >=======
    >Host  (192.168.1.254) appears to be up ... good.
    >Initiating SYN half-open stealth scan against  (192.168.1.254)
    >Adding TCP port 80 (state open).
    >The SYN scan took 8 seconds to scan 1523 ports.
    >For OSScan assuming that port 80 is open and port 1 is closed and neither
    >are firewalled
    >Interesting ports on  (192.168.1.254):
    >(The 1518 ports scanned but not shown below are in state: closed)
    >Port       State       Service
    >23/tcp     filtered    telnet
    >67/tcp     filtered    bootps
    >80/tcp     open        http
    >137/tcp    filtered    netbios-ns
    >514/tcp    filtered    shell
    >
    >TCP Sequence Prediction: Class=64K rule
    >                          Difficulty=1 (Trivial joke)
    >
    >Sequence numbers: 3EC519BD 3EC613BD 3EC70DBD 3EC807BD 3EC901BD 3EC9FBBD
    >Remote operating system guess: Accelerated Networks - High Speed Integrated
    >Access VoDSL
    >OS Fingerprint:
    >TSeq(Class=64K)
    >T1(Resp=Y%DF=N%W=2000%ACK=S++%Flags=AS%Ops=MNW)
    >T2(Resp=N)
    >T3(Resp=Y%DF=N%W=2000%ACK=O%Flags=A%Ops=)
    >T4(Resp=Y%DF=N%W=2000%ACK=O%Flags=R%Ops=)
    >T5(Resp=Y%DF=N%W=0%ACK=S++%Flags=AR%Ops=)
    >T6(Resp=Y%DF=N%W=0%ACK=O%Flags=R%Ops=)
    >T7(Resp=Y%DF=N%W=0%ACK=S%Flags=AR%Ops=)
    >PU(Resp=Y%DF=N%TOS=0%IPLEN=38%RIPTL=148%RID=E%RIPCK=0%UCK=0%ULEN=134%DAT=E)
    >
    >
    >Nmap run completed -- 1 IP address (1 host up) scanned in 8 seconds
    



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