We have continued to look into the MBR-wiping attacks that hit Korea earlier. We believe we now have a good picture of how the attack was conducted by looking into two different scenarios, why it caused so much damage, and how we were able to protect users using Trend Micro Deep Discovery and other solutions.
Spoofed Bank Notification Leads to Downloader
On March 19, we saw the first indications of this attack, where South Korean organizations received a spam message that contained a malicious attachment, including a supposed monthly credit billing information. The message posed as coming from a bank. The attachment is actually a downloader, which downloaded 9 files from several different URLs. To hide the malicious routines, a fake website is shown.
It was at this stage that Deep Discovery was able to protect our customers by heuristically detecting the malicious attachment via ATSE (Advanced Threats Scan Engine). Deep Discovery executed the attachment in a sandbox, which was used to generate a list of URLs that was used to block these attacks right away. The URLs found at this stage were then blocked. The combination of information provided by Deep Discovery and decisive actions by IT administrators was able to ensure our customers were protected in a timely manner.
The screenshot below shows the appearance of the alerts: