SINGAPORE - When Mohammad Adam Mohamed Rashid, 29, learnt how to exploit loopholes in the PayPal payment system, he went on to the dark Web.

According to online sources, special software is required to access the dark Web, and once inside, those browsing can access "darknet markets" where they can purchase illegal products.

It was in the "darknet markets" that Adam bought credit and debit card details, as well as PayPal's log-in credentials, as part of a scheme to commit cheating.

In one instance, he paid only US$30 (S$41) for a file containing numerous credit and debit card information.

Armed with such details, he went on an online shopping spree.

But he also bought a software program through the dark Web, designed to wipe his laptop's memory once he turns it off.

Deputy Public Prosecutor Stephanie Chew revealed this in a district court on Thursday (Nov 2) after Adam had admitted to 15 of 96 charges, including cheating and computer misuse. He was sentenced to three years' jail.

Adam's crime spree started sometime in April 2016, when he purchased the log-in credentials for numerous PayPal accounts belonging to other users via a website.

He then used the credentials to log into the PayPal accounts, and accessed the information stored in the account. These included the last four digits and expiry date of the credit card linked to the PayPal account, and the owner's e-mail address.

He would then change the log-in credentials to prevent the legitimate owner from accessing the PayPal account, and use the account to make online purchases before closing it.

Adam performed the sequence of events rapidly, usually within about five minutes. Items that he paid for were then either delivered to his home address or through a third party which would not require him to produce his identity card when collecting the item.

DPP Chew said Adam resold mobile phones he had purchased this way to a specific re-seller along Race Course Road who would not ask for his identification details.

About five months later, he accessed the illicit online marketplace "centralshop.ml" via the dark Web and bought the file containing numerous credit and debit card information.

Adam then used the stolen credit and debit card information to make numerous purchases, including electronic items, on a website called Station Go. He generally bought GoPro cameras and related accessories, and would resell them on online marketplace Carousell.

When his Carousell account was blocked in early November, he persisted in reselling the items by directly approaching buyers who had previously purchased from him.

He was arrested on July 11, 2016, but while on court bail, he reoffended. Adam was arrested again on Nov 29 the same year, after he had gotten rid of his mobile phone.

Besides cheating, he had also acquired $500 which a pair of brothers had transferred into his account to reward him for having taught one of them how to exploit the weakness in the PayPal system.

He received the money in his bank account, having grounds to believe that the amount represented the brothers' benefits from criminal conduct.

DPP Chew said the total amount involved across all the cheating and attempted cheating charges is $24,560. The amount in the proceeded cheating charges is $7,754. No restitution has been made.

Adam's lawyer Gino Hardial Singh said in mitigation that his client is contrite and remorseful for what he had done. But he is unable to recall why and how he committed these offences due to "dissociative amnesia".

Adam had suffered a loss of memory after he fell from a flight of stairs while in police custody last December, he said.

District Judge Chay Yuen Fatt, who said he has not come across such a case, noted that it was rather "unsettling" for most people who shop online.

"I think that's a factor I would consider very seriously. I think a deterrent sentence has to be imposed to deter this sort of offences," he added.