Cyber-thieves have turned to web programming languages to create a cheap ransomware service.
On infected machines, ransomware encrypts data and frees it only when victims pay for it to be unscrambled.
Many gangs making ransomware keep the code for themselves, but Ransom32 is freely downloadable from one dark web site.
News site BleepingComputer said Windows users had been targeted by the malware over the Christmas period.
Ransom32 was designed for those that lacked the technological skill to create their own brands of malware, said Bleeping computer editor Lawrence Abrams.
The malware can be downloaded from the dark web by anyone who supplies a Bitcoin wallet number,
The malware’s developers take a 25% cut of any ransom collected and forward the rest on to the Bitcoin wallet supplied.
Victims who unwittingly download the malware can be locked out of their computers and asked to pay a ransom in bitcoins to get back in.
The malware looks for and scrambles a huge variety of files including images, movies, documents and data archives.
Those who do not pay up could have their hard drives wiped.
Security expert Graham Cluley told the BBC: “By turning their ransomware into a sellable service, the criminals behind Ransom32 are providing an opportunity for other hackers to easily launch attacks that will encrypt users’ documents, including personal photographs, movies and more.”
“They demand payment via anonymous Bitcoin to ensure the safe return of the otherwise unrecoverable data.”
Those who use Ransom32 control it via a basic administration panel, that allows them to configure the malware to their liking.
The bug’s developers even offer them advice on fraud strategies, in one instance suggesting: “Don’t be too greedy or people will not pay.”
In a blog post, Fabian Wosar of security company Emsisoft said users’ best line of defence was “a solid” strategy for backing up files.
That way, should the worst happen, they can recover data without having to pay the ransom.
Mr Cluley added: “Presently, the attack appears to have been distributed via email, so once again users are advised to exercise great caution over what they run on their computers – especially if it arrives via unsolicited email.”