Researchers spotted a new wave of cyber attack from Russian speaking hacker who uses the weaponized TeamViewer to compromise and gain the full control of the Government network systems.
Teamviewer is the most popular tool used for remote Desktop control, desktop sharing, online meetings, web conferencing and file transfer between computers.
Based on the entire infection chain, tools developed and used in this attack, underground activity makes the researchers believe that the attack was conducted by a Russian Speaking hacker who is financially motivated.
Recent malicious campaign continuously makes use of TeamViewer by adding malicious TeamViewer DLL to Deliver Powerful Malware that Steals Sensitive Data and Money from various government and Financial networks.
Weaponized TeamViewer Infected Chain
The initial stage of the infection chain starts by delivering a spam email under the subject “Military Financing Program” with the attached malicious XLSM document with embedded macros.
A well-crafted malicious document posed as the U.S Department of State which is marks as a top secret to convincing the victims to open it.
Once the victims open the decoy document and enable the macro, there are two files are extracted from the hex encoded cells in XLSM document.
First one is a legitimate AutoHotkeyU32.exe program, the second one is a
AutoHotkeyU32.ahk which is an AHK script to communicate with C&C server to download the additional script and execute it.
There are 3 malicious AHK scripts are discovered that can perform different activities of following,
- hscreen.ahk: Takes a screenshot of the victim’s PC and uploads it to the C&C server.
- hinfo.ahk: Sends the victim’s username and computer information to the C&C server.
- htv.ahk: Downloads a malicious version of TeamViewer, executes it and sends the login credentials to the C&C server.
In this case, threat actors using DLL side-loading technique to load the TeamViewer DLL ( htv.ahk ) and this technique let attackers adding more functionality to TeamViewer.
Using this technique, attackers hiding the TeamViewer interface from the users view, saving the current TeamViewer session credentials to a text file and let them transfer and execution of additional EXE o DLL files .
According to Checkpoint Research, Once the attacker gain the remote access via malicious TeamViewer, one of the first uses of the AutoHotKey scripts is to upload a screenshot from the compromised PC.
Based on the Telemetry record, This attack targeting countries including Nepal, Guyana, Kenya, Italy, Liberia, Bermuda, Lebanon public financial sector and government officials.
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