Re: [PEN-TEST] Detecting the presence of a firewall

From: PinGer (chansimon99at_private)
Date: Wed May 16 2001 - 00:22:48 PDT

  • Next message: david.hyamsat_private: "Re: [PEN-TEST] Detecting the presence of a firewall / identifying firewalls"

    Hi andrew,
    
    I tried to scan my check point firewall using
    nmap -v -O -p256-258 -g53 -P0 -sS w.x.y.z
    without much success.
    
    * Can I know what switch combination did you use to elicit  the os
    information ?
    
    I'm actually doing a project on vulnerability assessment on my servers by
    scanning
    them from the external internet.
    my tool of choice is  Nmap.
    But I found that even though nmap scan ( -sS ) a range of port e.g. 1-60000
    (-p1-60000)
    in a random order
    it was always detected by the Firewall, in this case, Watchguard's Firebox
    and has
    its IP addressed blocked by the Watchguard which prevents it from further
    scanning.
    
    * Does Check point has a "blocked Site" feature like Watchguard ?
    
    * Has anybody succesfully try a udp scan (-sU)  thru a firewall (any type )?
    
    For those who uses Nmap
    * What is the most effective combination of switches you use to scan the
    Firewall and it network behind.
    
    my version : nmap -sS -F -o nmaplog.out -v -O x.w.y.z/24  -g53 -p1-60000
    
    * I found the Fin, Null and Xmas scan not that effective against a
    Checkpoint Firewall or
    any other firewall for the matter.
    
    Anybody has any opinion on it or better way to use nmap to enumerate the
    firewall or network ?
    
    
    I tried using other tools, like Firewalk 1.0, but I couldn't interpet the
    results :
    I entered a gateway host and a destination host :
    
    The Firwalk Control Panel
    53 source port                    33434 Initial ramping port
    0 network writing pause     1 redundancy count
    2 network time out pause    1 intial IP TTL
    1 expire vector                11-139,6000-6010    port scan list
    
    Firewalk scanning protocol : tcp/udp ( tried both )
    
    probe: 1 TTL : 1 port 33434: *
    probe: 2 TTL : 2 port 33434:*
    .
    .
    Hop count exceeded
    0 ports open, 0 ports unknown
    24 probes sent, 0 replies received
    
    I was certain that the destination host has port 80 opend but why didn't
    Firewalk detect it ?
    
    
    There a a couple of Vulnerabiltiy scanner out in the wild, like saint, sara
    e.g.
    * Has anybody tried using that to scan a network protected by checkpoint
    firewall or any other ?
    * Is there any white paper /docs on how to probe test your network /firewall
    ?
    
    
    
    Best Rgds,
    
    Simon
    Network Administrator
    
    
    ----- Original Message -----
    From: "Mule, Andrew" <AMuleat_private>
    To: <PEN-TESTat_private>
    Sent: Tuesday, May 15, 2001 1:49 AM
    Subject: Re: [PEN-TEST] Detecting the presence of a firewall
    
    
    
    True. These ports do provide evidence of the host being a CPFW. However,
    this assumes that mgmt is needed from a public location (ports 256,257,258).
    Any company concerned about corporate network security would not run these
    FW's with external mgmt ports enabled. So the new question is how do you ID
    a CPFW with these ports closed? A good answer, stated below, was NMAP with
    the -O option. This option will spit out something like this:
    
    Host  : X.X.X.X
    OS    : Check Point FireWall-1 4.0 SP-5 (IPSO build)
            Nokia IPSO 3.2-fcs4 releng 783
            NOKIA IPSO 3.2 Running Checkpoint Firewall-1
            Nokia IPSO 3.2-fcs4 releng 783 (FreeBSD Based)
    Ports : 53/tcp     closed      domain
            256/tcp    open        rap
            257/tcp    closed      set
            258/tcp    closed      yak-chat
    
    Host  : X.X.X.X
    OS    : Nokia IPSO 3.2-fcs4 releng 783
    Ports : 53/tcp     closed      domain
            256/tcp    open        rap
            257/tcp    open        set
            258/tcp    open        yak-chat
    
    Getting addresses behind a firewall can be difficult. Finding out where the
    web, mail or ftp servers usually point to the external IP address of the FW
    itself since arping is done by the FW for the client. I have been
    experiementing with Firewalk as well as modified TOS fields within the ICMP
    protocol to force identification of internal hosts but have not been
    successful....YET. If anyone has something to add to my madness please do so
    with care.
    
    
    Andrew A Mulé
    
    Network Security Architect
    
    Securify Inc.
    
    PGP: F2D5 54A4 F098 369E AA5E
             A64E 0F6F DE52 13C6 BAC5
    
    
    
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