"Some are real," he said.
The danger of Flexispy being secretly installed on a user's phone, however, is minimal compared with more malicious spyware reaching handsets in China, he said.
Each month, Kingsoft is finding more sophisticated spyware coming out of the country, Li said. In August it discovered a program that comes buried inside an apparently innocuous Android application, and which recorded phone calls and text messages without the user's knowledge. It's unclear why the program was developed. The creators might have been using it to collect data for marketing, which they could then sell to interested parties, Li said.
Several vendors of China's XWodi were contacted for this story, but all declined to be interviewed. Flexispy and Spyera would not reveal their exact sales figures. But aside from catching cheating spouses, the companies say their spyware products are generally used to monitor employees or track the activities of young children, teenagers, and elderly people unable to care for themselves.
Raihan maintained that he never intended his product to be used for illegal purposes. "There's enough business in the legitimate market. There's no need for it to be used in other situations," he said. Raihan later sold his Flexispy business to another company.
Whatever its merits, he is proof that the software can achieve its goal. After helping to build Flexispy, he gave his girlfriend at the time a mobile phone with the software installed on it. "Yes, she was cheating," he said. "I've used it ever since. It really opened my eyes."
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