QR codes on Twitter deliver malicious Chrome extension

The ISO file has two main components.
The _meta.txt contains a PowerShell script, which is encrypted with a substitution cipher.
The downloader.exe is a .NET assembly.
It has a big dictionary with the substitution alphabet to decrypt the PowerShell script in _meta.txt.
It adds the PowerShell commands as scheduled task named ChromeTask which runs every ten minutes.

Other variants of the same malware use dictionaries to combine words into a task name.
The downloader.exe also shows an error message to the user, claiming that the operating system is incompatible with the program.

https://www.gdatasoftware.com/fileadmin/web/general/images/blog/2022/01/chromeloader_main_msil.png

The PowerShell script downloads the Chrome extension archive.zip from a malware server and installs it.
Due to the scheduled task this continues to happen every ten minutes.
This explains why some Reddit users complain that Chrome closes itself all the time.
This is a mishap of the malware developer because the annoyance factor will make it more likely that affected users clean their system as soon as possible.

Malicious Chrome extension
The Chrome extension itself has not been analysed yet.
Possibly because of its hefty obfuscation.
While trying to debug the extension within Chrome, it’s already noted that the extension settings chrome://extensions are redirected to the general settings chrome://settings.
This prevents users from uninstalling the extension within Chrome.

The extension consists of four files.
The application icon is called properties.png and shows a gearwheel.
The manifest.json is part of every Chrome extension and has some metadata, e.g., about the icon location, extension name and permissions.
The config.js contains the name of the extension, version number, C2 server and some form of id named _dd which is always sent as parameter to the server.
https://www.gdatasoftware.com/fileadmin/web/general/images/blog/2022/01/chromeloader_config.png

The main script is the background.js.
It features control flow obfuscation via switch-case statement hopping which cannot be deobfuscated automatically by currently available tools.
JavaScript Deobfuscator is able to perform intial cleanup, but the code remains unreadable.
After identifying v0MM.T7 and v0MM.o7 as the ancor points for function string decoding, by replacing the calls to these functions with their return value.
A second pass to JavaScript Deobfuscator and manual cleanup of now unneeded functions leads to the final deobfuscated code.
https://www.gdatasoftware.com/fileadmin/_processed_/a/6/chromeloader_switchcase_7ff59485b5.png
https://www.gdatasoftware.com/fileadmin/_processed_/8/9/chromeloader_searchhijacking_1d475d62c9.png

The extension’s main functionality is to serve advertisments and hijack search requests to Google, Yahoo and Bing.
Every three hours analytics are sent to the C2.
The extension requests advertisments from the C2 server every 30 minutes.

The following image shows the extension’s request to the C2 server in the first line and the server response in the second. The server provided a direct download link for a legitimate software product.
https://www.gdatasoftware.com/fileadmin/web/general/images/blog/2022/01/chromeloader_adrequest.png

Sign Up For Threat Alerts

Loading...
Threats Icon

Dec 01, 2022

UNC4191 Threat Group Targets Entities In The...

The UNC4191 threat group was discovered targeting entities in the Philippines with custom malware and...

Threats Icon

Nov 30, 2022

Emotet Leads To Quantum Ransomware Infection

Threat actors were observed using Emotet to gain access to the victim's network and deploy...

Threats Icon

Nov 29, 2022

RansomExx Upgrades to Rust

IBM Security X-Force Threat Researchers have discovered a new variant of the RansomExx ransomware that...

Threats Icon

Nov 29, 2022

Ransomware Roundup: Cryptonite Ransomware

FortiGuard Labs has reported on Cryptonite ransomware, which was found to target Microsoft Windows machines...

Threats Icon

Nov 28, 2022

Operation Typhoon: The Cyber Sea Lotus Coveting...

Cyber espionage actors, now designated by FireEye as APT32 (OceanLotus Group), are carrying out intrusions...

Threats Icon

Nov 27, 2022

IL-Cert Alert – Active phishing campaign in...

There is a new phishing campaign in Israel. The malware relies upon user execution. The...

Threats Icon

Nov 27, 2022

Emotets Vacation Is Over: No Rest For...

Emotet started as a banking Trojan in spreading via spam campaigns by imitating financial statements,...

Threats Icon

Nov 24, 2022

Aurora: A Rising Stealer Flying Under The...

Aurora is a multipurpose botnet with data collection, information stealer, downloading, and remote access Trojan...

Threats Icon

Nov 23, 2022

Analysis Of The ViperSoftX And VenomSoftX Information...

Torrents and software-sharing sites are being used to target victims across the globe with variants...

Threats Icon

Nov 22, 2022

Wipermania

Wipers have existed for years, and while they haven't been utilized as much as ransomware,...

Threats Icon

Nov 21, 2022

LockBit 3.0 Ransomware Unlocked

Also known as LockBit Black, this ransomware family announced itself stating that it would now...

Threats Icon

Nov 21, 2022

Control Panel Executable Abused For QakBot Infection

QakBot campaign modifies deployment tactics and aims to exploit a DLL hijacking technique that abuses...

Threats Icon

Nov 20, 2022

Earth Preta Spear-Phishing Governments Worldwide

Trend Micro teams have been monitoring a wave of spear-phishing attacks targeting the government, academic,...

Threats Icon

Nov 20, 2022

CISA Alert (AA22-321A) – Hive Ransomware Analysis

Threat actors are using Hive ransomware variants to target the government, communication, critical manufacturing, information...

Threats Icon

Nov 16, 2022

DTrack activity targeting Europe and Latin America

DTrack is a backdoor used by the Lazarus group. It is used by the Lazarus...