Tag Archives: online banking

URLZone – a disaster waiting to happen

indepthreport-availableThanks to an effective PR strategy, most probably everybody has heard about URLZone by now. If not, you can find out more information regarding URLZone here or here.

We have been talking about it for some time and we already witnessed a few Trojans already using this technique. However, URLZone (or Bebloh) is now the first Trojan to come up with a professional setup to steal money from your account. Not only does it completely control your internet banking session, but it also automatically performs wire transfers to mule money accounts. If this isn’t bad enough, URLZone will then manipulate your online account statement to offset the fraudulent transaction (it can also remove the transaction or change the amount). The first time a victim would become aware of the fraudulent transaction(s) may be weeks or even months later – when they receive their paper statement in the mail! (that is if they get a paper statement at all… Lots of banks are trying to get rid of it altogether!)

Although real-time and session-based Trojans have been around for quite a while, they weren’t used in such a sophisticated way. An example was Yaludle (a Silentbanker variant), which injected HTML into the website that was dynamically retrieved from the web in real-time!

At the moment, only German banks are part of the URLZone configuration, but the bad guys can change the configuration at any second. Attacks against German online banks have always been very sophisticated simply because the German banks have employed one-time-password mechanisms (so called transaction numbers or TAN’s) for many years. Now the bad guys have found their way around it these mechanisms using such sophisticated techniques.

First generation attacks employing such Trojans saw the bad guys inject HTML code into the online banking login page to gather TAN’s in classical phishing attempts.

Then we saw more sophisticated attacks using variants of the well-known Bzub Trojan, which had the ability to perform wire transfers and remove them from the account statement.

Now we have URLZone doing silent wire transfers in the background and changing the online account statement.

Only as a result of the big amounts that these Trojans are fraudulently stealing are we beginning to hear about URLZone in the news, such as the recent $447,000 USD heist at Ferma in California, USA. While the manager had issued legitimate payments, the program initiated a further 27 transactions to various bank accounts, siphoning off a total of $447,000 USD in a matter of minutes. “They not only got into my system here, they were able to ascertain how much they could draw, so they drew the limit,” says Roy Ferrari, Ferma’s President (http://www.technologyreview.com/computing/23488/?a=f).

Another high-profile case was the gigantic Zeus botnet of recent, that also resulted in large amounts being stolen, such as the $415,000 USD heist at Bullitt County, Kentucky (http://voices.washingtonpost.com/securityfix/2009/07/an_odyssey_of_fraud_part_ii.html).

And let’s not forget Signs Designs Inc who also recently lost close to $100,000 USD in similar attacks (http://voices.washingtonpost.com/securityfix/2009/09/more_business_banking_victims.html).

In light of the above, I want to point out a few notes:

  • Firstly – The problem has been around for a long time and it seems that people are only doing something about such threats when they are large enough to be mentioned in the press. That’s exactly what the intelligent botnets such as Mebroot/torpig are exploiting. By staying under the radar and not being too greedy they can do their dirty work and don’t have to worry about consequences. Their motto seems to be: Just keep the security industry busy with non-threats like conficker and they won’t hassle you.
  • Secondly – This type of attack cannot be solved with 2-factor authentication.
  • Thirdly – While there is much hype around URLZone at the moment around how amazing and disturbing it is that the bad guys can do such things, we will always have this problem if the bank’s security and the user’s security systems are not connected.
  • Fourthly – While the Trojan is very, very sophisticated and advanced on the delivery side, they have made it incredibly easy for the good guys to catch them. Don’t expect this to happen in the future with new variants. We are still at the beginning…

One further thing to note is that since all real-time, session-based Trojans need to talk to a C&C server during the banking transaction, just one of TrustDefender’s many layers of protections will fully protect you against such attacks. Our “Secure Lockdown” knows all internet requests that belong to the financial institution and will block everything else while you are in a banking transaction. This will always protect you for all Trojans that work on this principle, not just for the likes of URLZone.

In addition, our Forensics Engine will also pick up the URLZone Trojan itself and will alert you of the infection, while also automatically disabling it for the period of the transaction. This will ensure you are always Safe and Secure while transacting online.

Due to popular demand, we have put together an in-depth TrustDefender Labs report about URLZone, which you can request by sending an email to labs@trustdefender.com. The in-depth report features the complete inner workings, together with an analysis of the configuration file and forensics information.

Silentbanker reloaded

indepthreport-availableIt’s been a while since we last looked at and analysed a Silentbanker Trojan in October 2008 and we have written about it on our blog at http://www.trustdefender.com/blog for some time.

The last couple of weeks/months have been quiet for Silentbanker, but now Silentbanker is back in action, very alive and kicking. We now have another detailed look at these new variants, how they now operate and how they have continued to evolve from last year.

The interesting fact is that it hasn’t evolved that much and they haven’t included too many new features. This is partly because the Silentbanker Trojan has already an impressive list of features, including HTTP(S) form sniffing, network tracing, session hijacking and html web injection capabilities.

The Silentbanker Trojan will only affect Internet Explorer and not any other Browsers as it is implemented as a Browser-Helper-Object (BHO).

However compared to the new top dogs who have stepped up the pace and gained extensive publicity such as Zeus, Mebroot/Torpig or Clampi, it seems nowadays the Silentbanker Trojan is a fairly average sophisticated Trojan, as Silentbanker only employs basic rootkit techniques, uses no encryption for upload of the stolen data and has a fairly basic C&C infrastructure. This – however – doesn’t mean that Silentbanker is not up to the task. It just shows how much innovation the bad guys have shown for the other Trojans.

But as the Silentbanker Trojan is completely silent and won’t slow down the computer at all, most users will not find any suspicious behaviour and we assume that it was very effective especially in its first couple of weeks of operation.

In conclusion, it becomes pretty obvious that the Silentbanker Trojan has fallen behind the likes of Mebroot/Torpig, Clampi or Zeus in terms of sophistication. While this may be perceived as good news, the bad news is that this means that the employed techniques still work and on top of that that the creators will for sure enhance the Silentbanker Trojan in the future. Watch this space…


We analysed the Silentbanker dropper with MD5 of e1e2b3389dd2e020ae2783b8c6c80a08 which had a Virustotal detection of 12/41, 29.27% (http://www.virustotal.com/analisis/112946f35cf76ed853b44aeaf837cc5c9ad15722e46637e3af1f82b4b122f41b-1252598004)

The inner workings haven’t changed too much from the Silentbanker Trojans we analysed around the same time last year in October 2008.
The dropper will install a Brower-Helper-Object (BHO) and register its payload dll into the Internet Explorer. The payload was in our case mscorewr.dll (in c:windowssystem32 folder) with a Virustotal detection of 9/41, 21.95% (http://www.virustotal.com/analisis/7b062ddb9dbc50cea53b98df892d4ceac003ece8551976085bd7ff57d5a5c664-1252582306).

The Silentbanker Trojan comes with a hard-coded C&C server which in our case was businessrest.cn (

Usermode hooks

Once the Silentbanker Trojan is active in memory (basically when the Internet Explorer starts), it will setup export hooks, so that it gets access to all transmitted internet traffic and to much more information.
Now, all sophisticated Trojans will hook core windows functions to compromise the system. Our Silentbanker Trojan hooked (or redirected) among others the following core windows functions: (full details available in the in-depth report)

  • HttpOpenRequestA/W
  • HttpSendRequestA/W
  • InternetConnectW
  • InternetReadFile
  • InternetReadFileExA/W
  • InternetWriteFile
  • CommitUrlCacheEntryA/W

As you can see, it basically hooks all Internet related functions to get access to the Internet Traffic (even though it might be encrypted with SSL or EV-SSL!)

These usermode hooks enable the Trojan to do its dirty work.

HTML Web injection

The Silentbanker Trojan has also the capability to inject any arbitrary HTML code into a website and it makes use of this mainly to get additional information from the user. The disturbing fact is however that this is also possible with HTTPS together with EV-SSL certificates. This way, the website looks legitimate from all angles. The URL is correct, the SSL certificate is fine and the green bar is shown. The reason is that the website actually comes from the legitimate site; however the Silentbanker Trojan will locally inject its malicious HTML code to the site. The code depends for each financial institution and is part of the configuration file.

A few examples are:



How to detect the Silentbanker Trojan

As the Silentbanker Trojan is a Browser-Helper-Object (BHO), you’ll see it appearing in the “Manage Add-ons” option of the Internet Explorer (From the Menu, choose “Tools” and then “Manage Add-ons”).
In our case the Trojan was called “mscorewr” and pretended to be a “Macrovision” component.

How TrustDefender protects you

As you would expect, TrustDefender protects you against Silentbanker from the very first second. TrustDefender employs a defence-in-depth strategy, and we are happy to say that every single component alone will protect you against Silentbanker.

  • Malicious BHO
    TrustDefender will automatically protect you from malicious Browser-Helper-Objects and makes sure that those components cannot penetrate the current session
  • Usermode Hooks
    As described before, this is how Silentbanker will get access to all its information. TrustDefender’s Forensics Analysis will pick up these hooks and disables these hooks for the current session
  • Secure Lockdown
    As Silentbanker works in realtime and will send the stolen credentials to its C&C server at the time of login, TrustDefender will automatically block this request as the Secure Lockdown will only allow internet requests that are associated with the current webservice (e.g. online bank).

Further Information

Further information can be obtained from the team at TrustDefender Labs. Just email us at labs@trustdefender.com.