RAT gets instructions from Yahoo Mail address.
One of the big challenges for malicious actors in operating a RAT (remote administration tool) is how to control the malware and retrieve data gathered from the infected machine. Listening on a certain port, or regularly connecting to a remote server, is behaviour that is likely to be spotted by intrusion detection systems.
Malware authors have become rather inventive in their efforts to control malware stealthily. ‘
Miniduke
‘, for instance, used specially created
Twitter
accounts to retrieve command and control URLs.
Today, we publish a paper by Paul Rascagnères, a researcher for German security firm
G Data
, in which he analyses a new RAT called IcoScript – which, until recently, had gone undetected since 2012.
The malware uses the Component Object Model technology in
Microsoft Windows
in order to get
Internet Explorer
to make HTTP requests to remote services. It also uses its own kind of scripting language to perform tasks.
What makes IcoScript unique is the fact that it connects to a
Yahoo Mail
account controlled by its authors to receive instructions – which are stored in specially crafted emails in the inbox. Access to webmail services is rarely blocked in corporate environments and the traffic is very unlikely to be considered suspicious.
Moreover, the modular nature of the malware makes it very easy for the attackers to switch to another webmail service, such as
Gmail
, or even to use services like
Facebook
or
LinkedIn
to control the malware while running a low risk of the communication being blocked.
The paper can be downloaded
here
in HTML format or
here
as a PDF.
If you are interested in stealthy techniques employed by malware, I recommend you read Paul’s interesting
analysis
of the ‘Poweliks’ malware that resides in the
Windows
registry.
Posted on 04 August 2014 by
Martijn Grooten
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