The cybercriminals behind the Necurs botnet are now taking screenshots of victims’ machines to improve the performance of their ransomware attacks, according to security researchers.

Experts at Symantec first disclosed a new Necurs downloader designed to gather telemetry data from infected computers, which could potentially help the cybergang determine when its ransomware is aimed at particularly lucrative victims. Any faulty issues with the downloader itself will be reported back to the Necurs team, which is responsible for malware such as Locky and the sinister TrickBot banking Trojan.

Necurs Spies on Victims to Refine Ransomware Attacks

According to ZDNet, there had been little evidence of activity from Necurs during the first half of the year. More recently, however, Locky ransomware attacks have been on the rise via messages laden with malware, suggesting that the cybercriminals behind the bot have been taking pains to make it even stronger.

Whereas a legitimate software company might lean on its users to alert them to problems, sending back error data and collecting screen grabs is the attackers’ way of bolstering Necurs’ effectiveness by themselves.

According to Gaurav Banga, CEO and founder of risk management firm Balbix, cybercriminals are acting less like rogue hackers and more like highly organized corporations who treat ransomware attacks as their product, SC Magazine reported. Potential victims will need to be even more organized and aware of the dangers before they’re hit.

Fortunately, the forces behind Necurs are not being very innovative in the area of phishing email messages. IT Wire reported that victims tend to receive something that looks like an invoice. Clicking on an embedded link then launches either Locky or TrickBot, infecting the user’s desktop and also taking screen shots as part of the infection process when the ransomware attacks begin.

An Ominous Threat

The latest downloader variant could mean that Necurs wants to spend less time targeting wary computer users, Bleeping Computer suggested. Telemetry data could help identify large enterprises where ransomware attacks could lead to bigger payoffs.

The fact that these cybercriminals are being so methodical in their approach — and so diligent about fixing their mistakes — makes Necurs a particularly ominous threat.