Nobu Ransomware

The Nobu Ransomware is a file-locking Trojan that stops documents and similar media from opening. As part of the STOP Ransomware family, its encryption is secure against free recovery methods, and users should save backups securely for restoring any affected content. Compatible anti-malware products also can protect Windows systems by blocking or removing the Nobu Ransomware on sight.

Far from Stopping at the Media Hostage-Taking Game

The STOP Ransomware grows long in the tooth. Still, its age isn't keeping threat actors from distributing it to vulnerable targets, with all the effectiveness of its yesteryear attacks in modernized payloads. Variants of this Ransomware-as-a-Service, such as the Kodg Ransomware, the Maas Ransomware, the Reha Ransomware, or the Sglh Ransomware, sometimes see drastic changes to encryption for improving their extortion chances. However, with the Nobu Ransomware, its differences are more about randomly-generated characters.

Samples of the Nobu Ransomware of interest to malware experts all use randomly-generated-reminiscent names, such as 'd4f5,' without disguising the EXE or executable format. This choice is one that many STOP Ransomware versions use, implying that attackers either drop the file manually or use indirect download-and-drop methods, such as a first-stage Trojan embedded inside an e-mailed document. However, this Ransomware-as-a-Service has an extremely flexible range of targets and infection vector possibilities.

The Nobu Ransomware only targets Windows systems, although it can damage home users' work just as easily as a compromised corporate network. Features concerning victims include encryption (which blocks media like documents or pictures through AES and an RSA key), deleting the Restore Points, and blocking websites via the Hosts file's settings. The latter is a semi-unique property of the Nobu Ransomware's family and usually interferes with accessing Microsoft.com and other cyber-security company sites.

Systematic Stopping Points for the STOP Ransomware Updates

Although the randomization of the Nobu Ransomware's installer names well represents the RaaS's natural agility, Windows users should establish environments that are at low risk from attacks by file-locking Trojans. The Nobu Ransomware delivers text (and, most likely, HTA, although unconfirmed) ransom demands that offer a premium service for recovering anything that it blocks. Victims are better off servicing themselves through already-saved backups on other devices outside of the Nobu Ransomware's grasp, such as password-secured cloud servers or removable devices.

Most Windows users also will find that stopping traditional infection methods for this family is a non-demanding chore. Using safe passwords will prevent attackers from taking over accounts. Disabling RDP access will remove the most obvious of unintentional backdoor opportunities. Avoiding illegal or unsafe download sources like torrents will steer clear of many Trojan bundles. Malware experts also encourage disabling macros, JavaScript, Java, and Flash, and being cautious about e-mail attachments – even ones that seem workplace-pertinent.

Of course, trustworthy vendors' anti-malware services will detect and remove the Nobu Ransomware, although many companies flag this variant with a generic name.

Concerning its campaigning name, the Nobu Ransomware is another four-character randomization that, like its installer names, lacks any particular meaning. Users may speculate at their leisure about unrevealed details of its attacks, but, whether or not they do so, they should have backups well in hand.