Melissa Strip Captcha Breaker Trojan
I bet you have never seen such a tempting Trojan before. The Trojan named Melissa Strip, identified as TROJ_CAPTCHAR.A by TrendMicro and Trj/RompeCaptchas.A by Panda is a very polite one as it asks you on start up whether you want to play a game. If you do, you basically start a game where you need to enter captchas correctly for the trojan to strip for you.
After clicking Start Play the image of a women on the left side and a captcha on the right is displayed. The program asks you to enter the captcha to see another picture of the woman with less clothes on. After entering the captcha correctly and clicking on enter the Trojan loads another picture and captcha asking the user again to type the correct code to see Melissa strip even more.
You might have already guessed that the captcha is actually the captcha of another website, Yahoo for instance, and the Trojan uses the help of users to enter those captchas correctly on those websites. Captchas are used to tell human users from bots apart and make it more difficulty to create automatic process to signup or submit data.
The Trojan does not seem to cause harm on the users system. It simply uses the input to create correct responses to captcha codes that are used to create accounts on websites like Yahoo Mail.
Trend Micro reports that the Trojan most likely arrives as a file downloaded or via other malware on the system. It may also be distributed via email attachments, one of the most common forms of distributing malware.
It is recommended to delete the program right away and scan your system with up to date antivirus software such as Malwarebytes Anti-Malware to remove all traces of the program from your system.