Malicious Rich Text Format (RTF) documents are often used to spread malware, and a recent attack campaign targeting the Israeli public sector has been using RTF files to inject the Zeus Trojan.
Security researchers at Check Point have identified a series of attacks after a high-profile client submitted a malicious RTF file for analysis. The file had been received my multiple employees via spam email, and the security firm found that it had been sent to multiple people working for various Israeli public sector organizations.
According to the security firm, the malicious campaign targeted over 200 machines across 15 distinct Israeli firms and institutions, including government agencies, security industry firms, municipal agencies, research institutions and even hospitals. Almost half of the attacks in this campaign were targeted at Israeli organizations, and Check Point suggests that they might have been politically motivated.
The RTF document was found to be infected with the Zeus Trojan, which is usually targeted at enterprise environments to steal passwords, financial credentials, FTP login details, cookies, mail settings, and other authentication details. Moreover, Check Point explains that the malicious document was auto-generated by Microsoft Word Intruder (MWI), a well-known exploit kit.
An in-depth analysis of the document revealed that the Trojan was sending an HTTP GET request to a C&C server, which was, in fact, used to monitor several campaigns, each with a different payload. Log files recovered from the server revealed that most of the IP addresses targeted by the campaign were in Israel.
This happened mainly because, after receiving the malicious RTF file via the aforementioned spam email, employees opened it, and the payload was executed. The campaign reportedly targeted the Israeli public sector for several months before being identified and disrupted, but no details on its purpose or on the bad actors behind it have been revealed as of now.
“Such campaigns are usually orchestrated by adversaries which are themselves nation-states or political organizations. On the other hand, campaigns launched by such adversaries tend to make use of dedicated tools that are specifically tailored for the occasion. It is unusual for such a campaign to rely on ‘off-the-shelf’ materials such as MWI and vanilla Zeus,” Check Point explains in a blog post.
Malicious campaigns using variations of the notorious Zeus malware are not uncommon. In late August, banking Trojan Sphinx, built on Zeus code, went up for sale for $500, after researchers discovered another sophisticated variant of Zeus in early 2015.