Downloading unofficial and pirated software from the Internet carries a significant risk of malware infections. Malware is often packaged with the installers or with the cracks/key generators that provide the serial keys or codes to activate the software.

Cybercriminals use a variety of methods for driving traffic to their malicious websites, including malicious Google Ads, adverts on other third-party ad networks, SEO poising to get their malicious sites appearing high in the search engine listings, and via torrent and warez sites. A warning has recently been issued about the latter by AhnLab Security Intelligence Center (ASEC).

The campaign identified by the researchers distributes Microsoft Office, Microsoft Windows, and the Hangul Word Processor. The pirated software is available through torrent sites and includes a professional-looking installer. The installer for Microsoft Office allows users to select the Office products they want to install in either the 32-bit or 64-bit version and select the language.

If the installer is run, the user will get the software they are looking for; however, in the background, a malware cocktail will be installed. The threat actor behind this campaign is distributing several different malware payloads, including coinminers, remote access trojans (RATs), downloaders, and anti-AV malware.

When the installer is run, an obfuscated .NET downloader is executed which connects to the attacker’s Telegram/Mastadon channels and obtains a Google Drive or GitHub URL from where Base64 encrypted strings are obtained. Those strings are decrypted on the device and are PowerShell commands. Task Scheduler is used to execute the PowerShell commands, which install the malware. The scheduled tasks also allow the threat actor to consistently install other malware variants on the infected device.

By using Task Scheduler, the threat actor can reinstall malware if it is detected and removed, and since an updater is installed, the PowerShell commands can change. Even if the initial URLs are blocked, others will be added to ensure malware can still be delivered.

Initially, the threat actor was installing the updater together with either the Orcus RAT or the XMRig cryptocurrency miner. Orcus RAT provides the threat actor with remote control of an infected device, and has keylogging capabilities, can take screenshots, access the webcam, and exfiltrate data. XMRig is configured to only run when it is unlikely to be detected and will quit when system resource usage is high.

In the latest campaign, the threat actor also installs 3Proxy, which allows abuse of the infected device as a proxy, PureCrypter for downloading and executing additional malware payloads, and AntiAV malware, which disables antivirus and other security software by modifying the configuration files.

While this campaign appears to be targeting users in South Korea, it clearly shows the risks of downloading pirated software. Due to the inclusion of the updater and the installation of PureCrypter, remediation is difficult. Further, new malware variants are being distributed every week to evade detection.

Employees often download software to make it easier for them to do their jobs, and Torrent sites are a common source of unauthorized software. Businesses should therefore implement policies that prohibit employees from downloading software that has not been authorized by the IT department and should also implement controls to prevent Torrent and other software distribution sites from being accessed.

With TitanHQ’s WebTitan DNS filter, blocking access to malicious and risky websites could not be simpler. Simply install the cloud-based web filter and configure the solution by using the checkboxes in the user interface to block access to these categories of websites. WebTitan is constantly updated with the latest threat intelligence to block access to known malicious websites, and it is also possible to block downloads of executable files from the Internet.

For more information on improving Internet security with a DNS-based web filter, give the TitanHQ team a call. WebTitan, like all other TitanHQ products, is available on a free trial, with product support provided to ensure you get the most out of the solution during the trial.