Cybercriminals have inevitably taken advantage of the publicization of the Ebola virus in the news for several months. We've spotted a couple of malicious spam samples that reference the Ebola virus in the last week. The image below shows an example of one such e-mail purporting to be from the World Health Organization. The attached file poses as a document about Ebola virus safety tips.
Upon closer inspection, the RAR compressed file attachment is not a document file but an executable file of a DarkComet Remote Access Trojan (RAT). This Trojan makes use of its heavily obfuscated AutoIt-based script to run undetected by antivirus software.
When run, it creates a randomly named folder in the Windows Application Data folder and drops all of its component files into that folder. The dropped files include the following:
%AppData%\eaedq\dhkta.bvi (6KB) - AutoIt script for decrypting other component files%AppData%\eaedq\ttskj.urv (121KB) - Encrypted AutoIt script%AppData%\eaedq\kjofr (678KB) - Encrypted AutoIt script%AppData%\eaedq\YMQGIX (29KB) - RAT configuration file%AppData%\eaedq\nxjqw.cmd (750KB) – AutoIt script loader executable
The malware also created these autorun registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run WindowsUpdate = "%AppData%\eaedq\nxjqw.cmd %AppData%\eaedq\dhkta.bvi"
And it also created this infection mark registry:
HKEY_CURRENT_USER\Software\DC3_FEXEC
The Trojan stays memory-resident by running a legitimate Microsoft .NET services installation tool named RegSvcs.exe and then injecting itself to that process.
The Backdoor Trojan saves key logs to a folder in the Application data directory:
C:\Documents and Settings\\Application Data\dclogs\(year)-(month)-(day)-(digit).dc
Other than keylogging, it is capable of the following backdoor functionalities:
The RAT then sends all of this stolen information to a remote server with the IP address of 5.254.112.46 at port 3030.
We've only seen one sample from this campaign so far. At this time we don't have reason to believe it is a widespread campaign. The address it was sent to was an old honeypot address, so it's not exactly targeted either. These facts taken together suggest a low volume campaign (sent to whatever address list the spammer is using) in an attempt to infect random users in the hope of gaining some data that can be used or sold.
Another Ebola-themed spam campaign that we spotted claims to be from the Mexican Government's advisory of the Ebola situation in Mexico.
When opening the attached document file, the text instructions and screenshots entice the user to enable the Macro feature in the Microsoft Word application to load the content as seen below.
Enabling macros then triggers the AutoOpen macro and consequently downloads a malware executable from a remote server, which you can see in the image below. Recently we have seen a rise in the number of these Word macro malware attachments in spam email, using a range of subject themes. Ebola is just another convenient theme for the bad guys to latch onto.
Other Ebola-themed spam messages we've noticed are more of a nuisance than malicious. We've noticed the messages coming from a single bot we internally call Type 52. In October, we've tracked a small spike of these unsolicited emails that contain links pointing to ads, gaming forums or pharmaceutical websites.
Here are some of the Subject lines being used.
Conclusion:
Unsurprisingly, cybercriminals continue to piggyback on newsworthy and major events, disasters and outbreaks to lure potential victims and spread their malware.
Just last week the United States Computer Readiness Team (US-CERT) published an advisory warning users of scams and spam campaigns using the Ebola virus as a social engineering theme. We are echoing their recommendation of never clicking unsolicited web links or attachments in email messages, particularly those with an Ebola theme.
Trustwave's Secure Email Gateway (SEG) customers are protected from these spam campaigns.
