Disguising Exfiltrated Data
There’s an interesting article on a data exfiltration technique.
What was unique about the attackers was how they disguised traffic between the malware and command-and-control servers using Google Developers and the public Domain Name System (DNS) service of Hurricane Electric, based in Fremont, Calif.
In both cases, the services were used as a kind of switching station to redirect traffic that appeared to be headed toward legitimate domains, such as adobe.com, update.adobe.com, and outlook.com.
The malware disguised its traffic by including forged HTTP headers of legitimate domains. FireEye identified 21 legitimate domain names used by the attackers.
In addition, the attackers signed the Kaba malware with a legitimate certificate from a group listed as the “Police Mutual Aid Association” and with an expired certificate from an organization called “MOCOMSYS INC.”
In the case of Google Developers, the attackers used the service to host code that decoded the malware traffic to determine the IP address of the real destination and redirect the traffic to that location.
Google Developers, formerly called Google Code, is the search engine’s website for software development tools, APIs, and documentation on working with Google developer products. Developers can also use the site to share code.
With Hurricane Electric, the attacker took advantage of the fact that its domain name servers were configured, so anyone could register for a free account with the company’s hosted DNS service.
The service allowed anyone to register a DNS zone, which is a distinct, contiguous portion of the domain name space in the DNS. The registrant could then create A records for the zone and point them to any IP address.
Honestly, this looks like a government exfiltration technique, although it could be evidence that the criminals are getting even more sophisticated.