Summerschool Aachen 2004/Network Reconnaissance Lab

Notes on Presentations

Fingerprinting

We also worked on our mandatory assignemt. Our idea was basically first to parse the http://cr.yp.to/surveys/dns1.html page with a perl script and load the fingerprints into our datastructure, into which also the fingerprints of the ftp and smtp servers were to be loaded. We planed to use the already implemented functions which computed the fingerprint of a server and pipe their output to our script and compare it with the stored values in our datastructure. When calling our script the user was expected to give it as a parameter value n and our script was supposed to output for the best n matches of our fingerprint with the fingerprints stored in our datastructure the name of the corresponding server.

--Samad Nasserian

Notes on Lab Session

SNMP Reconnaissance

This is a placeholder for the results of the SNMP scanning I've been doing, but here's a list of default passwords that others might find useful

-- Stephen Lewis

Fingerprinting

So we gave out some mandatory work for today. It was considered boring and frustrating by most and they considered all other possibilities more entertaining. Is that a patter about the grass being greener elsewhere? Alexander seemed to consider the requirement of doing something he doesn't enjoy for a whole afternoon to hard and left without notice. I'm disappointed about that.

To find out if the task was really unbearable I sat down myself and implemented what I asked for. The basic parser was quickly done:

    def loadFingerprints(self): 
        # seek list of probes 
        for l in sys.stdin: 
            if 'Here are the DNS packets sent by the surveying program:' in l: 
                break 
        for l in sys.stdin: 
            if l.startswith('<tr><td align=right>'): 
                fields = l.split('<td>') 
                # this IS exploiutable 
                tests.append((eval(fields[1].strip('</>tdtr')), fields[2].strip('</>tdtr</td></tr>\n'))) 
            if '</table>' in l: 
                break 
 
        # seek list of probes 
        for l in sys.stdin: 
            if not l.startswith('<tr><td>'): 
                continue 
            if l.startswith('<tr><td>Software</td>'): 
                continue 
            probes.append([x.replace('</td>', '').replace('tr>', '').strip(' </\n') for x in l.split('<td>')])

Crude, but works. Mostly. I get entries like

[, 'BIND 9.2', '4q', '5', '5', '1q', '2', '1q', '1q', '1q', '1q', '3AA', '0AA', '3AA', '3AA', '3AA', '3AA', '3AA', '4q', '4q', '4q', '3AA', '3AA', '5', '0AAD, 2, 5']

that is fine, but others are not

[, '1', '1', 't', 't', 't', 't', 't', 't', '1', 't', '0', 't', '0', '15', '0Z0', '0', '0', 't', 't', 't', '0', '0', 't', '4']

I decided to leave that problem for later.

Scaning was easy now:

     def scanTargets(self, targetlist, timeout=1): 
        for target in targetlist:
            s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) 
            s.settimeout(timeout)
            s.connect((target, 53)) 
            for test, desc in tests: 
                flags = []    
                reply = None 
                retries = 5 
                while 1: 
                    print 'sending %r ...' %test, 
                    s.send(test) 
                    try: 
                        reply = s.recv(1500)     
                        print repr(reply) 
                        break   
                    except socket.timeout: 
                        print "timeout"
                        retries -= 1 
                        if retries < 0: 
                            flags.append('t') 
                            break
                if reply: 
                    flags.extend(self.checkFlags(reply)) 
                print "xxx", flags 

I did parse the response:

    def checkFlags(self, reply): 
 
        flags = [] 
        u = DNS.Lib.Munpacker(reply) 
        r = DNS.Lib.DnsResult(u, []) 
        # check RCODE 
        flags.append(r.header['rcode']) 
        if r.header['tc']: 
            flags.append('TC') 
        if r.header['rd']: 
            flags.append('RD') 
        if r.header['aa']: 
            flags.append('AA') 
        if r.answers: 
            flags.append('D') 
        if len(r.questions) == 0: 
            flags.append('q') 
        if len(r.questions) == 0: 
            flags.append('Q2') 
        # X is missing 
 
        # print vars(r) 
        return flags 

But I failed to implement matching against the fingerprints database. I also got far to much timeouts to my DNS queries. I didn't investigate further. :-(

-- MaxDornseif