mSpy, the makers of a dubious software-as-a-service product that claims to help more than two million people spy on the mobile devices of their kids and partners, appears to have been massively hacked. Last week, a huge trove of data apparently stolen from the company’s servers was posted on the Deep Web, exposing countless emails, text messages, payment and location data on an undetermined number of mSpy “users.”

mSpy has not responded to multiple requests for comment left for the company over the past five days. KrebsOnSecurity learned of the apparent breach from an anonymous source who shared a link to a Web page that is only reachable via Tor, a technology that helps users hide their true Internet address and allows users to host Web sites that are extremely difficult to get taken down.

The Tor-based site hosts several hundred gigabytes worth of data taken from mobile devices running mSpy’s products, including some four million events logged by the software. The message left by the unknown hackers who’ve claimed responsibility for this intrusion suggests that the data dump includes information on more than 400,000 users, including Apple IDs and passwords, tracking data, and payment details on some 145,000 successful transactions.

The exact number of mSpy users compromised could not be confirmed, but one thing is clear: There is a crazy amount of personal and sensitive data in this cache, including photos, calendar data, corporate email threads, and very private conversations. Also included in the data dump are thousands of support request emails from people around the world who paid between $8.33 to as much as $799 for a variety of subscriptions to mSpy’s surveillance software.

It’s unclear exactly where mSpy is based; the company’s Web site suggests it has offices in the United States, Germany and the United Kingdom, although the firm does not appear to list an official physical address. However, according to historic Web site registration records, the company is tied to a now-defunct firm called MTechnology LTD out of the United Kingdom.

Documents obtained from Companies House, an official register of corporations in the U.K., indicate that the two founding members of the company are self-described programmers Aleksey Fedorchuk and Pavel Daletski. Those records (PDF) indicate that Daletski is a British citizen, and that Mr. Fedorchuk is from Russia. Neither of the men could be reached for comment.

Court documents (PDF) obtained from the U.S. District Court in Jacksonville, Fla. regarding a trademark dispute involving mSpy and Daletski state that mSpy has a U.S.-based address of 800 West El Camino Real, in Mountain View, Calif. Those same court documents indicate that Daletski is a director at a firm based in the Seychelles called Bitex Group LTD. Interestingly, that lawsuit was brought by Retina-X Studios, an mSpy competitor based in Jacksonville, Fla. that makes a product called MobileSpy.

U.S. regulators and law enforcers have taken a dim view of companies that offer mobile spyware services like mSpy. In September 2014, U.S. authorities arrested a 31-year-old Hammad Akbar, the CEO of a Lahore-based company that makes a spyware app called StealthGenie. The FBI noted that while the company advertised StealthGenie’s use for “monitoring employees and loved ones such as children,” the primary target audience was people who thought their partners were cheating. Akbar was charged with selling and advertising wiretapping equipment.

“Advertising and selling spyware technology is a criminal offense, and such conduct will be aggressively pursued by this office and our law enforcement partners,” U.S. Attorney Dana Boente said in a press release tied to Akbar’s indictment.

Akbar pleaded guilty to the charges in November 2014, and according to the Justice Department he is “the first-ever person to admit criminal activity in advertising and selling spyware that invades an unwitting victim’s confidential communications.”

Unlike Akbar’s StealthGenie and some other mobile spyware products, mSpy advertises that its product works even on non-jailbroken iPhones, giving users the ability to log the device holder’s contacts, call logs, text messages, browser history, events and notes.

“If you have opted to purchase mSpy Without Jailbreak, and you have the mobile user’s iCloud credentials, you will not need physical access to the device,” the company’s FAQ states. “However, there may be some instances where physical access may be necessary. If you purchase mSpy for a jailbroken iOS phone or tablet, you will need 5-15 minutes of physical access to the device for successful installation.”

A public relations pitch from mSpy to KrebsOnSecurity in March 2015 stated that approximately 40 percent of the company’s users are parents interested in keeping tabs on their kids. Assuming that is a true statement, it’s ironic that so many parents have now unwittingly exposed their kids to predators, bullies and other ne’er-do-wells thanks to this breach.

Tags: Aleksey Fedorchuk, Hammad Akbar, Mobile Spy, Mspy hack, MTechnology LTD, Pavel Daletski, Retina-X Studios, StealthGenie, Tor, U.S. Attorney Dana Boente