dnsenum Returning Odd Characters After Installing Options Perl Modules On Backtrack 5
Posted by alex in Errors at 12:31 AMWhile working on an upcoming article for QD I ran into an issue with the dnsenum.pl Perl script. I followed the process of installing the optional Perl modules and when I went back to test dnsenum it would no longer return any IP addresses. Instead of dnsenum returning actual IP addresses it was returning odd characters. It turns out there is some form of conflict between dnsenum.pl and the Net::DNS Perl module. Below I describe the dnsenum issue in more detail and provide a work around by manually downgrading the Net::DNS Perl module by hand.
dnsenum.pl On Backtrack Linux Returning Odd Characters Instead Of IP’s:
root@bt:/pentest/enumeration/dns/dnsenum# perl dnsenum.pl example.com dnsenum.pl VERSION:1.2.2 ----- example.com ----- Host's addresses: __________________ example.com 869 IN A Bty% Name Servers: ______________ pdns01.domaincontrol.com 15799 IN A �E�2 pdns02.domaincontrol.com 15799 IN A �m�2 Mail (MX) Servers: ___________________ ASPMX.L.GOOGLE.com 119 IN A J}� ALT1.ASPMX.L.GOOGLE.com 91 IN A ��J ALT2.ASPMX.L.GOOGLE.com 235 IN A ��K ASPMX2.GOOGLEMAIL.com 137 IN A ��J ASPMX3.GOOGLEMAIL.com 269 IN A J}� Trying Zone Transfers and getting Bind Versions: _________________________________________________ Trying Zone Transfer for example.com on pdns02.domaincontrol.com ... AXFR record query failed: NOTIMP Unable to obtain Server Version for pdns02.domaincontrol.com : NOTIMP Trying Zone Transfer for example.com on pdns01.domaincontrol.com ... AXFR record query failed: NOTIMP Unable to obtain Server Version for pdns01.domaincontrol.com : NOTIMP brute force file not specified, bay. root@bt:/pentest/enumeration/dns/dnsenum#
As you can see in the output above the locations where IP addresses should display are some form of encoded output instead of four octets of numbers. After some troubleshooting I was able to isolate the issue to be related to the Net::DNS Perl module. After downgrading 6 times I was able to locate a version of the Net::DNS Perl module that outputs the IP addresses properly. Below I show the process of manually downgrading Net::DNS to resolve the issue with dnsenum.pl.
Download & Install The Net::DNS 0.68 Perl Module On Backtrack Linux:
I would assume the issue is actually with the dnssnum.pl script being outdated since there have been 4 minor releases since the bug was introduced. The same issue occurs in latter versions of Net::DNS after the base 0.68 release on January 31, 2012. The latest version of dnsenum was released in June of 2011 so again it is likely something changed in Net::DNS and/or Perl and dnsenum is truly the culprit here. Regardless it doesn’t matter much since dnsenum is the tool we want to use! Follow the steps below to manually downgarde the Net::DNS Perl module.
Download The Net::DNS Perl Module Version 0.68: click here
root@bt:/usr/local/src# wget http://backpan.perl.org/authors/id/N/NL/NLNETLABS/Net-DNS-0.68.tar.gz root@bt:/usr/local/src#
Unpack Net::DNS Version 0.68:
root@bt:/usr/local/src/# tar -zxvf Net-DNS-0.68.tar.gz Net-DNS-0.68/ Net-DNS-0.68/contrib/ Net-DNS-0.68/contrib/loc2earth.fcgi Net-DNS-0.68/contrib/dnswalk.README Net-DNS-0.68/contrib/check_zone Net-DNS-0.68/contrib/loclist.pl Net-DNS-0.68/contrib/README ....output cut off.... root@bt:/usr/local/src/#
Enter Directory And Generate Net::DNS Makefile Using Perl:
root@bt:/usr/local/src/# cd Net-DNS-0.68 root@bt:/usr/local/src/# root@bt:/usr/local/src/Net-DNS-0.68# perl Makefile.PL Testing if you have a C compiler and the needed header files.... You have a working compiler. Activating Non Fatal Online Tests... Warning! ======== Online tests depend on conditions beyond the control of Net::DNS. The tests check for the expected results when both Net::DNS and the outside world are functioning properly. In case of failure it is often undecidable if the error lies with Net::DNS or elsewhere. The libraries needed to support IPv6 transport have not been found. You will need recent versions of the IO::Socket::INET6 and Socket6 libraries (from CPAN). Checking if your kit is complete... Looks good Writing Makefile for Net::DNS root@bt:/usr/local/src/Net-DNS-0.68#
The above example output has generated the Makefile in the Net-DNS-0.68 directory. Now lets compile and install the 0.68 version of Net::DNS on our Backtrack Linux server.
Compile And Install Version 0.68 Net::DNS On Backtrack Linux:
root@bt:/usr/local/src/Net-DNS-0.68# make Skip blib/lib/Net/DNS/RR/A.pm (unchanged) Skip blib/lib/Net/DNS/Resolver/Win32.pm (unchanged) Skip blib/lib/Net/DNS/RR/Unknown.pm (unchanged) Skip blib/lib/Net/DNS/RR/IPSECKEY.pm (unchanged) Skip blib/lib/Net/DNS/RR/EID.pm (unchanged) Skip blib/lib/Net/DNS/RR/ISDN.pm (unchanged) Skip blib/lib/Net/DNS/RR/HIP.pm (unchanged) Skip blib/lib/Net/DNS/RR/MX.pm (unchanged) Skip blib/lib/Net/DNS/Header.pm (unchanged) ....output cut off.... root@bt:/usr/local/src/Net-DNS-0.68# root@bt:/usr/local/src/Net-DNS-0.68# make install Files found in blib/arch: installing files in blib/lib into architecture dependent library tree Installing /usr/local/lib/perl/5.10.1/auto/Net/DNS/DNS.so Installing /usr/local/lib/perl/5.10.1/Net/DNS.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Packet.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/DomainName.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Text.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Mailbox.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Domain.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Question.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/RR.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Resolver.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Header.pm Installing /usr/local/lib/perl/5.10.1/Net/DNS/Nameserver.pm ....output cut off.... root@bt:/usr/local/src/Net-DNS-0.68#
Now that we have downgraded Net::DNS we should see IP’s again in the standard output from running dnsenum.pl. Below there is an example of the same command run in the first example above showing the difference in outputs between the two.
dnsenum.pl Perl Script Outputting IP Address Information On Backtrack Linux
root@bt:/pentest/enumeration/dns/dnsenum# perl dnsenum.pl example.com dnsenum.pl VERSION:1.2.2 Host's addresses: __________________ example.com 1800 IN A 192.168.121.37 Name Servers: ______________ pdns01.domaincontrol.com 13404 IN A 216.69.185.50 pdns02.domaincontrol.com 13636 IN A 208.109.255.50 Mail (MX) Servers: ___________________ ASPMX.L.GOOGLE.com 68 IN A 74.125.133.27 ALT1.ASPMX.L.GOOGLE.com 256 IN A 173.194.74.27 ALT2.ASPMX.L.GOOGLE.com 45 IN A 74.125.131.27 ASPMX2.GOOGLEMAIL.com 224 IN A 173.194.74.26 ASPMX3.GOOGLEMAIL.com 204 IN A 74.125.131.26 Trying Zone Transfers and getting Bind Versions: _________________________________________________ Trying Zone Transfer for example.com on pdns02.domaincontrol.com ... AXFR record query failed: NOTIMP Unable to obtain Server Version for pdns02.domaincontrol.com : NOTIMP Trying Zone Transfer for example.com on pdns01.domaincontrol.com ... AXFR record query failed: NOTIMP Unable to obtain Server Version for pdns01.domaincontrol.com : NOTIMP brute force file not specified, bay. root@bt:/pentest/enumeration/dns/dnsenum#
After further testing it appears that not all of dnssnum’s functions work properly but I will go into that more in a future article. For now we are confident we can at least read the output returned by the dnsenum.pl Perl script.
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