A serious payment glitch was diagnosed in the work of Overstock.com, an online retail giant. This malfunction allowed customers to pay with either Bitcoin or Bitcoin Cash interchangeably, which is a problem because the two cryptocurrencies have a huge difference in their valuations. As a result of the glitch, Overstock customers were able to buy any item at a rock-bottom price. Anyone paying with Bitcoin could repeatedly use the authorized bitcoin refund amount on any canceled Overstock orders.
Brian Krebs, a journalist of Krebsonsecurity.com, was the first to report the problem and reach Overstock.com for the comment. When he purchased solar lights worth $78.27 from the site, Overstock instructed him to send 0.00475574 in Bitcoin to their address. Krebs sent 0.00475574 in Bitcoin Cash instead of sending bitcoins, and this was accepted. This meant Krebs paid only $12.02 for the lights. The refund he requested was given back by Overstock in bitcoin worth $77.80. “A dishonest customer could have used this bug to make ridiculous sums of bitcoin in a very short period of time,” said Krebs.
According to the data from Krebsonsecurity.com, the company changed no code in its site and a fix implemented by Coinbase resolved the issue.
Overstock.com commented: “We were made aware of an issue affecting cryptocurrency transactions and refunds by an independent researcher. After working with the researcher to confirm the finding, that method of payment was disabled while we worked with our cryptocurrency integration partner, Coinbase, to ensure they resolved the issue. We have since confirmed that the issue described in the finding has been resolved, and the cryptocurrency payment option has been re-enabled.”
Coinbase said that the issue was “caused by the merchant partner improperly using the return values in our merchant integration API” and pointed out that no other Coinbase customer had such a problem.
Overstock.com is a tech-driven online retailer founded in 1997. It initially sold exclusively surplus and returned merchandise on an online e-commerce marketplace. In 2010 the company reported its first billion-dollar year, in 2011 it started rebranding.
On January 9, 2014, Overstock.com partnered with Coinbase in order to let customers use Bitcoin in paying for merchandise. After that Overstock.com became one of the first large e-commerce vendors to accept the virtual currency. During the checkout process for those paying by bitcoin, Overstock.com provides the customer a Bitcoin wallet address that can be used to pay the invoice and complete the transaction.
In late 2017 the price of Bitcoin amounted to more than $17,000 per coin, and on December 19, 2017, Coinbase added support for Bitcoin Cash, a branch of Bitcoin designed to address the cryptocurrency’s scalability challenges. As a result of the change, Coinbase customers with balances of Bitcoin were given an equal amount of Bitcoin Cash stored by Coinbase.