April 2008

Q: Cisco Site to Site VPN

New week a new question, in this case the question is a bit more generic and I believe raises a few dilemmas, feel free to take a shot at it:

Hi Experts,

Is it secure to just configure Cisco IPSEC/GRE site to site tunnel without firewall/IPS/IDS. The argument here is although it is internet facing, there is only a host to host routing between the routers and the default route goes to the tunnel. Am I right to say that it is technically secure since the router only route traffic between the designated routers?

Thanks in advance.

J. O.

Q: Outlook attachments

Another one for you this week, we especially liked XenoMuta’s answer to our previous one.
Lets go:

Dear SecuriTeam,

i am not sure if you are able to help us to find a solution for a special problem but i’ve tried everything and spent a lot of time in the internet without any achievement.

we want to export the content of multiple exchange servers from our branch offices into personal folders (.pst files) and import these informations into our exchange mail system. the main problem why we are not yet able to do this is that we want to scan the content for viruses, worms (if possible with multiple virus scanners) and for unwanted content like videos, music, executables and so on and this in a way that a real content scan would be done instead of just checking against the file extension. also all attached archives (zip, rar etc.) should be opened (if possible) and scanned for its content. if an attachment is found which cannot be scanned because of password protection or encryption or whatever reason this attachment or the complete mail should be deleted or moved to a quarantine area.

Thank your very much for your support

Best regards
J. B.

Arrested for security research?

Anyone who has ever done serious security research reached the line that separates good from evil. If you are working with phishing emails you get links to kiddie porn. If you research security holes you deal with exploits. If you are researching botnets you are up to your neck in sensitive information that was obtained illegally.

I’m sometimes asked if we ever get ‘tempted’ to cross over. The answer is simple: we may think like criminals and sometimes emulate their work, but it never ever enters our mind to do something malicious. Finding an SQL injections that gives you full access to the database is fun; using this information to steal money or order items for free is light years away from what we do.

But not everyone understands that, and that’s scary. A member of the THC got pulled over at Heathrow airport by the UK government. The story has a happy ending, but it must have been scary, not to mention frustrating. My good friend Zvi Gutterman found weaknesses in the Windows and Linux PRNG. Breaking the PRNG has consequences – while top-secret crypto systems will not use the standard Windows or Linux random number generators, who knows if there is a simple Linux based basic communication device used in one of the governments? An applicable weakness in the PRNG may have a serious impact and they might decide that shutting up Zvi is easier than replacing all their units.

If you think the previous paragraph is a paranoid conspiracy theory, lets talk about kiddie porn links. These pop up whenever we deal with botnets, phishing and malware. The police is trying to demonstrate zero tolerance for kiddie porn, usually by arresting anyone who has visited such an illegal web site. How will you explain to your family, when they see you on the 8 o’clock news arrested for kiddie porn charges, that you are not a dangerous paedophile but you had no idea the link you clicked was to a kiddie porn site?

There will be more incidents like the THC one. We can all tell the difference between a proof of concept device to show how vulnerable GSM encryption is and an illegal wiretapping device. But the law officials can’t, and often don’t seem to care about the difference. Some of the time it’s not even law officials: Fyodor had his site shut down to prevent spreading his nmap ‘hacking tool’. Dmitry Sklyarov was arrested in Las Vegas for breaking the PDF encryption. In the Fyodor incident the decision was made by godaddy. In the Dmitry Skylarov case it was Adobe who got the court order.

I wouldn’t want to see security research being a licensed profession (like a private detective license or a license to carry a firearm) – I’ve seen brilliant teenagers who think out of the box and find vulnerabilities no one else can, but are not old enough to drive a car. So what else can we do to make sure we hold a ‘get out of jail’ card?

Q: THC PPTP Bruter

Once again – another security question from our readers to the security experts who read this blog:

I ran across your site looking for information regarding the security of PPTP. I then found the PPTP bruter program from THC. I am a small business owner. I am a VAR (value added reseller) of POS (point of sale) equipment. My POS equipment is usually windows PC’s running POS software. I install a SOHO router that is also a PPTP endpoint so I can VPN in and remotely administrator my clients systems.

I’m trying to find out how easy it would be for someone to hack my PPTP endpoint. Can you help me figure out how to test my router?


K. L.

A new WMF attack looming?

It appears that a new WMF attack is coming, as you recall about a year back an WMF vulnerability was used on several high profile sites to infect visitors, this now appears to start happening again.

The first sign of this is the appearance of exploits for the vulnerability, starting off with version specific and evolving into a generic one.

The second sign is web sites being infect with hidden iframe that redirect to a javascript code that is at the moment dormant, or refers to non-existing domains.

The last stage is those javascripts getting modified, or the non-existing domains poping up into existing, you got yourself an infection.

It is time to start your vulnerability assessment engines, make sure all your windows based machines are tested, verify that your website passes a web site audit, and lastly get updated as this news item evolves.

Marketer on Marketer crime

I have a strong distrust of most marketing and sales individuals. I hate evaluating software and getting a dozen calls or emails from some overzealous, inside-sales weenie. For this reason, I usually use bogus information when I fill out the obligatory form requesting the software that I want to play with. Lately, a lot more companies have been ignoring my queries for eval software. While I’m pleased to not be receiving calls or emails, I would appreciate the actual software. Today, while waiting (not too patiently) for my link to come through, I went through the email looking for some clue as to why I wasn’t selected to play with their software. In the HTML, I note a line like this (obfuscated somewhat and using ‘(‘ and ‘)’ instead of angle brackets).

(IMG xsrc=”http://somelargesoftwarecompany.com/mk/auth?_ED=abcdefghijklmnopqrstuv

&_esniff=true” HEIGHT=”1″ WIDTH=”1″)

What’s that? Why is HEIGHT and WIDTH equal to 1? How will I ever see that?

So, the natural next question is: What happens when the web browser (or email client) requests that image. Well, it turns out it’s not a real image. It’s size is 0 bytes and the error code is “204 NoContent”.

I add a single quote to the abcdefghijklmnopqrstuv string. Now, I’m getting an error message like:

“MarketFirst encountered an error while processing your request.”

So, what’s the deal with that little, bitty image? Well, it turns out that I’m not supposed to see that little, bitty image. That little snippet is part of a marketing software (MarketFirst) which tracks when and where the email is opened (ooooh, I am *so* hating marketing guys right now).

To see other companies using the marketfirst software, google:
MarketFirst error inurl:”/mk/”

Even more fun, google:
MarketFirst inurl:”/mk/” ODBC error

Wanna try it yourself. Check out:

You’ll even get your own email which tracks back to their database…call it marketer on marketer crime.

Now, if I could just get a MarketFirst demo evaluation 😉


P.S. and here’s how to bypass marketer profiling and get your software downloads. Open the email in plain text (it’s MIME encoded). Convert it to HTML text. Post the HTML on some web site. Now, call your buddy at a Fortune50 company and have him/her click the link. I bet you get the download now.

P.S.S Even more fun….embed the HTML in an email to some user at the same company where you are requesting the download :)

Manual Vishing

This Hebrew post in linmagazine describes what first sounds like a typical Vishing attack. The author’s mother receives a phone call telling her there’s been a terrible accident and she needs to call the hospital for the details. They give her the ER’s number but tell her to use only her land line. The number is *7200526671955. Strange, but not unusual in Israel where dialing *pizza connects you to Dominos and *mortgage to your local sub prime pusher.
So she calls and calls but there’s no answer, and she rings her son to tell him to try and call.

He rings, and gets a voicemail. Getting suspicious he dial his phone company’s information directory and finds they were conned: *720 is the code for call forwarding, and 052-667-1955 is a local cell number. It’s a clever scheme, actually. All the for-pay phone numbers (sex hotlines, etc) are opt-in which means they are blocked by default (to prevent scams like this, among other things).
However, calls to cellular phones are more expensive (in Israel the caller pays the charge and not the receiver) and so it is possible to cut a deal with the cellular company for revenue sharing and open your own ‘recipe tips’ hotline which should bring in many incoming cellular calls and make everybody (especially the mobile operator) happy. If instead of recipes you make people call because their friend’s phone lines are automatically forwarded to your number, well that doubles the fun.

So these guys figured call forwarding to international numbers won’t work, and chose the mobile option. Although it’s a bit risky (you need to be able to collect the money from the cellular operator before the cookie jar slams shut) but sounds lucrative. Now comes the final step in a Vishing scam like this; you need to convince a lot of people to do the call forwarding, and for that you usually use a Voice-over-IP line with a pre-recorded message. But not these guys: the post’s author confirmed to me that his mother spoke to a flesh-and-blood voice who actually answered her questions, had a perfect Hebrew accent (it wasn’t a Nigerian who went to Jewish Sunday school) and told her the number to call twice (and even waited until she grabbed a pen).

Calling manually is risky: people can trace back the call and find out where you were. Hiring telemarketing is typically out of the question (lets just try to imagine the brief to the telemarketing team) and manually calling hundreds of people is really not cost effective.

So why the manual call? The only thing that comes to mind is they were beta testing or watching to see the response from the cellular company or law agencies. Maybe they are even using Israel as a beta site for an international Vishing attack? When the FBI or secret Service (or Israeli Police) catch them, I hope they ask. With a bit of luck they’ll post a hint here in the comments.

Open source pollenation

I’m rushing this post out so that this post can be the 1,000th post :)

I’ve got a project that I’d love to run, but I just don’t have the time. Here’s what I’m thinking of. I want to crawl Fortune 1000 sites and generate fingerprints on their code (ASP, JavaScript, whatever I can read in plain text). I then want to pull out variable names and other unique identifiers from the culled code. With this, I can:

1) see if there has been any cross-pollenation across the sites

2) See if any of these Fortune 1000 web developers have embedded open source code within their app.

3) If (2), I’d like to run the open source code through a static source code analyzer and see if there are any ‘gotchas’.

A few months ago, I did this exercise for a single Fortune 1000 company. I wasn’t really surprised to find a bunch of open source libs in use. In this particular case, I didn’t even need to use google codesearch to find the package that they were using. The company had left all the GNU comment info within the source. It also wasn’t surprising to find that the developers had installed the entire open source project under an ‘include’ directory, even though my spider only found a link to several of the ‘.js’ files. And, lastly, searching bugtraq for this particular product revealed that they were running an older, vulnerable version of their open source software. Mildly interesting. I’d love to automate this. A cool product would:

1) spider a site and download all their code (even HTML can have comment fields or variable names which can be used to track the HTML back to an open source app)

2) Use some algorithm to find uniq identifiers within the code. Store these identifiers.

3) Use some algorithm to compare these identifiers to other sites which have already been spidered and stored.

4) Feed these identifiers to ‘google codesearch’ to see if the code is part of a larger, open source project.

5) If (4) use some algorithm to determine the version level. Query bugtraq for flaws within the observed version.

6) Run the code through some static analyzers looking for coding flaws.

That’s it. Happy 1,000-post birthday Securiteam blogs!