Some malware developers have taken to copyrighting their work, according to Symantec.
The security company highlighted in its blog that Russian malware developers have been adding copyright rules to the programs they sell illegally on the internet.
In the terms and conditions of Zeus - a malware program Symantec investigated - the copyright states purchasers must not freely distribute the software once they've bought it. The licence also gives the malware writer the right to charge for any update to the product in the future as well as demanding the code is not reverse engineered.
The malware developers also highlighted in the terms and conditions that if the copyright is broken the code for the malware will be passed onto antivirus companies.
"Despite the clear licensing agreement and the associated warnings, this package still ended up being traded freely in underground forums shortly after it was released," says Liam Ouch author of the blog.
"It just goes to show you just can't trust anyone in the underground these days," he adds.