A malvertising campaign has been detected that delivers two forms of malware: The new, previously unknown Vidar information stealer and subsequently, the latest version of GandCrab ransomware.

The packaging of multiple malware variants is nothing new of course, but it has become increasingly common for ransomware to be paired with information stealers. RAA ransomware has been paired with the Pony stealer, njRAT and Lime ransomware were used together, and Reveton ransomware is used in conjunction with password stealers.

These double-whammy attacks help threat actors increase profits. Not everyone pays a ransom, so infecting them with an information stealer can make all infections profitable. In many cases, information can be obtained and sold on or misused and a ransom payment can also be obtained.

The latest campaign uses the Vidar information stealer to steal sensitive information from a victim’s device. The Vidar information stealer is used to obtain system information, documents, browser histories, cookies, and coins from cryptocurrency wallets. Vidar can also obtain data from 2FA software, intercept text messages, take screenshots, and steal passwords and credit/debit card information stored in browsers. The information is then packaged into a zip file and sent back to the attackers’ C2 server.

The Vidar information stealer is customizable and allows threat actors to specify the types of data they are interested in. It can be purchased on darknet sites for around $700 and is supplied with an easy to use interface that allows the attacker to keep track of victims, identify those of most interest, find out the types of data extracted, and send further commands.

Vidar also acts as a malware dropper and has been used to deliver GandCrab ransomware v5.04 – The latest version of the ransomware for which no free decryptor exists.

While many ransomware variants are delivered via spam email or are installed after access to systems is gained using brute force tactics on RDP, this campaign delivers the malicious payload through malvertising that directs traffic to a websites hosting the Fallout or GrandSoft exploit kits. Those EKs exploits unpatched vulnerabilities in Internet Explorer and Flash Player. The campaign targets users of P2P file sharing sites and streaming sites that attract large amounts of traffic.

Infection with the Vidar information stealer may go undetected. New malware variants such as this may be installed before AV software malware signatures are updated, by which time highly sensitive information may have been stolen, sold on, and misused. If GandCrab ransomware executes, files will be permanently encrypted unless a ransom is paid or files can be recovered from backups.

Businesses can protect against attacks such as these by ensuring that all operating systems and software are promptly patched. Drive-by downloads will not occur if the exploits for vulnerabilities used by the exploit kit are not present.

An additional, important protection is a web filter. Web filters prevent users from visiting websites known to host exploit kits and also sites that commonly host malicious adverts – torrents sites for instance. By carefully controlling the sites that employees can access, businesses can add an extra layer of protection while avoiding legal liability from illegal file downloads and improving productivity by blocking access to non-work-related websites.

For further information on web filters for businesses and MSPs, contact the TitanHQ team today.