Dutch users were recently targeted in a website compromise that involved a popular news site in the Netherlands, nu.nl. The site was compromised and modified to load a malicious iframe that resulted to visitors’ systems being infected with a SINOWAL variant.
Trend Micro researcher Feike Hacquebord says that considering the different characteristics of this attack, it seems like it was specifically designed to affect Dutch users. Aside from the affected site being one of the most popular sites in their country, the scripts inserted in the website were activated right before lunch time in the Netherlands — a time when Dutch users usually utilize to check the news and other sites while in the office.
According to nu.nl’s released statement, they believe that attackers exploited a vulnerability on the news group’s Content Management Systems (CMS), allowing them to insert 2 scripts — g.js and gs.js — in nu.nl’s subdomain.
Investigation reveals that the scripts, detected by Trend Micro as JS_IFRAME.HBA, are highly-obfuscated scripts that when executed lead users to yet another script, specifically one that loads various exploits.
This exploit kit, detected as JS_BLACOLE.HBA, was found to be the Nuclear Pack exploit kit. Upon execution, it checks the affected system for any vulnerable software, and then downloads any applicable exploit that can run successfully.
Based on the analyzed code of the exploit pack, systems with the following unpatched application versions could be possibly infected with this threat:
- Adobe Reader versions in between 8 and 9.3
- Java versions in between 5 and 6 and between 5.0.23 and 6.0.27
Aside from the software above, Nuclear Pack Exploit Kit is also capable of exploiting vulnerabilities in Windows components like Microsoft Data Access Components (MDAC), Help and Support Center (HCP), and Microsoft Office Web Components (OWC) Spreadsheet.
A successful exploit will then lead to the download of the downloader TROJ_SMOKE.JH, which then downloads the SINOWAL variant, TROJ_SINOWAL.SMF. At the time of the infection, Trend Micro already detected this SINOWAL variant.
TROJ_SINOWAL.SMF collects information about the affected system such as:
- System’s hard disk serial number
- Running processes
- Software registered in the HKLMSOFTWAREMicrosoftWindowsCurrentVersionUninstall registry key
TROJ_SINOWAL.SMF is also said to download another component that is capable of infecting the MBR of an affected machine.
Data gathered from the Trend Micro™ Smart Protection Network™ reveals that most of the users who attempted to access the URL used by JS_BLACOLE.HBA when the site was loading malicious files were indeed from the Netherlands:
Hours after the compromise was discovered, nu.nl was clean again. Sadly, this compromise had already exposed some of the site’s visitors to SINOWAL infection. Thus users are advised to check their system for possible infection and perform the necessary removal instructions that are available on the Internet. As for us, Trend Micro products detect the related files used in the attack, as well as block all the malicious domains used, all through the Trend Micro Smart Protection Network. The command-and-control (C&C) servers to which this SINOWAL variant sends information to are also blocked by Trend Micro.
Hat tip to security evangelist Ivan Macalintal for additional insights and analysis.