Last March, I blogged about the Andromeda, a well-known botnet that surfaced in 2011 and is making a comeback this year. Just months after my report, we are still seeing notable activities from the said botnet, in particular a sudden boost of GAMARUE variants last week. The Andromeda botnet is a spam botnet that delivers GAMARUE variants, which are known backdoors and have a noteworthy way of propagating via removable drives.
We’re keeping track of the GAMARUE infection for the past weeks and observed some noteworthy activities. For the past 30 days, we noticed a sudden spike of its variants on May 17. In particular, there was a 82% increase from May 16 – May 17 and another 32% on May 18. A significant bulk of these malware, specifically 63%, is WORM_GAMARUE variants.
Figure 1. GAMARUE detection for the past 30 days (April 20 – May 31)
In my initial blog entry, I reported that the bulk of infection came from Australia. Last year, Germany was also one of the most GAMARUE-affected countries. However, just months after my first post, we are seeing a trend in which a majority of WORM_GAMARUE variants are affecting India, Turkey, and Mexico.
Figure 2. Top countries affected by WORM_GAMARUE
Currently, we can not readily determine why GAMARUE variants increased on the said dates. If anything, this trend shows that the botnet is still active and poses risks to users.
Andromeda Botnet: Old Threat Repackaged
In our 2013 1Q Security Roundup, we concluded that during this quarter, cybercrime was characterized by old threats made new. The Andromeda spam botnet is a good example of this trend, this time with aid of the Blackhole Exploit kits (BHEK) and some new neat tricks.
This threat arrives as a spammed message containing a malicious attachment (GAMARUE variants) or links leading to certain sites, which now include those compromised by the notorious Blackhole Exploit kit. GAMARUE variants are known to propagate via removable drives. It also drops component files instead of copies of itself to make detection difficult. Taking cue from threats like DUQU and KULUOZ, GAMARUE variants also uses certain APIs to inject itself to normal process to evade detection.
Propagating techniques aside, GAMARUE variants have backdoor capabilities since it communicates with certain C&C servers to send and receive commands. This communication, in effect, gives a remote malicious user control over the infected system. Some of the commands the malware can execute include downloading other malware onto the system, most notably info-stealing threats like ZeuS/ZBOT variants.
Because some Andromeda-related spam messages eerily looks like legitimate email notification from commercial services (flight, hotel, courier services etc.), the usual criteria for determining a spam are not sufficient. As an alternative, you can verify to see if the email you’ve received is legitimate or not. Since BHEK is known to exploit software vulnerabilities like Java, you must always update your system with the latest security patch or re-consider your use of Java. For better protection, install antimalware software like Trend Micro, which protects your system from spam, malicious URLs, and malware.
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