Security experts at Cisco Talos are warning of a new sophisticated espionage campaign targeting NATO Governments with specially designed documents used to deliver Flash exploits. The campaign started during the Christmas and New Year holidays, the hackers used Word document titled “Statement by the NATO Secretary General following a meeting of the NATO-Russia Council” as bait.
The attacks aim to perform reconnaissance activity on infected systems and avoid sandboxes. The researchers dubbed the framework “Matryoshka Doll Reconnaissance Framework” due to its complexity.
The content of the document has been copied from an official NATO statement published on its website and the RTF file does not contain any exploits, both circumstances make hard for the victims to detect the attack.
The malicious document contains a succession of embedded objects, including OLE and Adobe Flash objects, that are extracted in a specific order.
“The OLE object contains an Adobe Flash object. The purpose of the Adobe Flash is to extract a binary blob embedded in itself via ActionScript execution,” reads a blog post . “This blob is a second encoded and compressed Adobe Flash object. The encoded algorithm is based on XOR and zlib compression. This is the second Adobe Flash in the final payload located within the document.”
The analysis of the payload revealed its most relevant component is located in the ActionScript. The first action of the ActionScript is to contact a specific URL of the C&C.
In this way, the attacker gathers information about the target, including the OS version or the Adobe Flash version that are used to evaluate if attack the machine or not.
The collected data can allow the attacker to determine if the infected system is a sandbox or a virtual machine and stop the operations.
At this point, the malicious code performs two additional nested requests that use data obtained from the response to the previous request.
In the final phase of the attack, a Flash exploit is fetched, decoded and executed.
Talos observed a significant traffic on the C&C domain starting with January 16, it was mainly composed of requests coming from the security research community.
The attacker noticed the source of the request and decided to replace the malicious payload with junk data in order to interfere with an investigation conducted by the principal security firms.
“It’s important to note that the actor realized security researchers were poking around their infrastructure and then rigged the infrastructure to create resource issues for some security devices. These are the characteristics of reasonably advanced attackers who have designed an efficient minimalist framework that was able to adapt purposes on the fly.” states the analysis.
(Security Affairs – NATO, Spear Phishing)