Symantec researchers have uncovered a previously unknown attack group that is targeting government and military targets, including several overseas embassies of an Eastern European country, and military and defense targets in the Middle East. This group eschews custom malware and uses living off the land (LotL) tactics and publicly available hack tools to carry out activities that bear all the hallmarks of a cyber espionage campaign.
The group, which we have given the name Gallmaker, has been operating since at least December 2017, with its most recent activity observed in June 2018.
Tactics and tools
The most interesting aspect of Gallmaker’s approach, according to Symantec, is that the group doesn’t use malware in its operations. Rather, the attack activity we observed is carried out exclusively using LotL tactics and publicly available hack tools. The group takes a number of steps to gain access to a victim’s device and then deploys several different attack tools, as follows:
- The group delivers a malicious Office lure document to victims, most likely via a spear-phishing email.
- These lure documents use titles with government, military, and diplomatic themes, and the file names are written in English or Cyrillic languages. These documents are not very sophisticated, but evidence of infections shows that they’re effective.
- These lure documents attempt to exploit the Microsoft Office Dynamic Data Exchange (DDE) protocol in order to gain access to victim machines. When the victim opens the lure document, a warning appears asking victims to “enable content” (See Figure 1). Should a user enable this content, the attackers are then able to use the DDE protocol to remotely execute commands in memory on the victim’s system. By running solely in memory, the attackers avoid leaving artifacts on disk, which makes their activities difficult to detect.
- Once the Gallmaker attackers gain access to a device, they execute various tools, including:
- WindowsRoamingToolsTask: Used to schedule PowerShell scripts and tasks.
- A “reverse_tcp” payload from Metasploit: The attackers use obfuscated shellcode that is executed via PowerShell to download this reverse shell.
- A legitimate version of the WinZip console: This creates a task to execute commands and communicate with the command-and-control (C&C) server. It’s likely this WinZip console is used to archive data, probably for exfiltration.
- The Rex PowerShell library, which is publicly available on GitHub, is also seen on victim machines. This library helps create and manipulate PowerShell scripts for use with Metasploit exploits.
Gallmaker is using three primary IP addresses for its C&C infrastructure to communicate with infected devices. There is also evidence that it is deleting some of its tools from victim machines once it is finished, to hide traces of its activity.
Targets and timeline
Gallmaker’s activity appears to be highly targeted, with its victims all related to government, military, or defense sectors. Several targets are embassies of an Eastern European country. The targeted embassies are located in a number of different regions globally, but all have the same home country.
The other targets Symantec has seen are a Middle Eastern defense contractor and a military organisation. There are no obvious links between the Eastern European and Middle Eastern targets, but it is clear that Gallmaker is specifically targeting the defense, military, and government sectors: its targets appear unlikely to be random or accidental.
Gallmaker’s activity has been quite consistent since Symantec has started tracking it. The group has carried out attacks most months since December 2017. Its activity subsequently increased in the second quarter of 2018, with a particular spike in April 2018.
Symantex says Gallmaker’s activity points strongly to it being a cyber espionage campaign, likely carried out by a state-sponsored group.
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