Botnets are no longer in vogue, with so-called ransomware having overtaken them as the main threat to enterprises.

Security outfit Trend Micro Inc. said that its analysis shows that file-encrypting ransomware accounted for 83 percent of all “data extortion” attacks in the fourth quarter of 2015.

The most notorious strain of ransomware is known as CryptoWall, which was used in 31 percent of all attacks. The extreme effectiveness of CryptoWall was highlighted in a report from the Cyber Threat Alliance last November, which revealed that the ransomware had netted its creators an astonishing $325 million so far.

Those revenues were traced through the monitoring of Bitcoin wallets and other techniques, and show that a growing number of enterprises who fall victim to the malware are simply coughing up whatever amount is asked of them in order to retrieve their data.

The majority of victims come from the healthcare sector, Trend Micro said in its Annual Security Roundup Report. In 2015, 30 percent of all ransomware attacks targeted healthcare firms, followed by educational organizations (17 percent) and government sectors (16 percent).

Trend Micro also warned of the growing danger of Internet of Things (IoT) attacks, as more connected devices enter the enterprise.

The problem is that many IoT devices are extremely vulnerable to attacks, in many cases much more so than regular computers and mobile devices. The problem is exacerbated by the fact that IoT devices run on numerous different operating systems, which means system updates and data protection become even more complex.

You can check out Trend Micros’ study in full here.

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