More than 12.5 million email accounts were hit with the infamous Necurs botnet, and within six hours were victims of an attack involving Scarab ransomware, according to security researchers.
Texas-based antivirus firm Forcepoint reported that victims were targeted across the U.S., U.K., France, Germany and Australia around Nov. 23. Those infected by Scarab found their machines locked by cybercriminals, who demanded a ransom payment in bitcoin to recover stolen files.
A Time-Sensitive Dilemma
Like other ransomware attacks spread by botnets, the fraudsters behind this attack used simple phishing emails that pretend to come from a printer manufacturer such as Epson, HP, Canon or Lexmark, according to the International Business Times. The messages included a zip folder that appeared to contain real files that had been scanned by a third party.
The behavior of Scarab is interesting because it adds a misspelled version of the word “support” to the files it has encrypted and then uses Notepad to relay the ransom message, according to the Forepoint report. The message walks through the nature of the threat and even includes a primer on how to get bitcoin.
Perhaps more alarming, the message notes that the price of the ransom depends on the speed at which victims respond to the extortion. To pay up, victims can opt to use Bitmessage, a communication tool for the bitcoin community, or simply send an email to an attacker-controlled address specified in the message. This puts victims in a challenging position, given the speed at which botnets can spread this type of infection.
The Necurs Botnet Is Old News
Although the Scarab ransomware only emerged this past summer, Bleeping Computer noted that the use of botnets such as Necurs to give fraudsters immediate global reach is a long-standing trend.
In this case, it’s possible that more than one cybergang joined forces to use Necurs and Scarab in tandem. This could make tracking down the culprits — let alone recovering lost or hijacked files — even more difficult for security researchers.
Writer & Editor
Shane Schick is a contributor for SecurityIntelligence.