Upbit briefly suspends Aptos withdrawals following security incident

South Korea’s largest cryp­to exchange, Upbit, has resumed deposits and with­drawals of Aptos (APT) tokens after abrupt­ly halt­ing the ser­vice due to a secu­ri­ty incident. 

In a state­ment on Sat­ur­day, Upbit said it had detect­ed an “abnor­mal deposit attempt” while mon­i­tor­ing Aptos trans­ac­tions, accord­ing to a rough trans­la­tion from Google.

Fol­low­ing an inspec­tion of its wal­let sys­tem, the exchange con­firmed sta­bil­i­ty for Aptos deposits and with­drawals has been restored and actions have been tak­en against the abnor­mal activity.

The inci­dent gained pub­lic atten­tion when var­i­ous Upbit users report­ed unau­tho­rized deposits of what appeared to be Aptos tokens (APT) in their accounts, accord­ing to X user Defi­nal­ist. Block­works has reached out to Upbit to confirm.

It was lat­er dis­cov­ered that these were not gen­uine Aptos tokens but “scam” tokens named ClaimAPT­Gift. Upbit cus­tomer ser­vice report­ed­ly con­tact­ed users who had sold these fraud­u­lent tokens, ask­ing for refunds.

The prob­lem, Defi­nal­ist said, lay in Upbit’s wal­let sys­tem fail­ing to ver­i­fy the types of tokens being deposit­ed properly. 

Nor­mal­ly, the sys­tem should dif­fer­en­ti­ate between native Aptos tokens and oth­er tokens with­in the same ecosys­tem. But due to a glitch, all tokens sent via a spe­cif­ic func­tion were rec­og­nized as Aptos tokens, lead­ing to the issue.

On a decen­tral­ized exchange, users can check the token address on-chain using a block explor­er, such as Ether­scan on Ethereum, to con­firm whether a giv­en token is authen­tic. A cen­tral­ized plat­form, how­ev­er, requires cus­tomers to trust the exchange’s inter­nal nam­ing system.

Crisis averted

A lucky break mit­i­gat­ed the sever­i­ty of the inci­dent. The scam tokens had six dec­i­mal places, while native Aptos tokens have eight. 

If both had eight dec­i­mals, users could have received and poten­tial­ly sold $25,000 instead of $250, risk­ing a severe mar­ket dis­rup­tion, Defi­nal­ist said.

Upbit’s offi­cial notice also cau­tioned users to pay “spe­cial atten­tion to the price dif­fer­ences with oth­er exchanges” as trad­ing resumes, acknowl­edg­ing that the price may fluc­tu­ate dras­ti­cal­ly due to the incident. 

The price of APT surged around 9% fol­low­ing the inci­dent, and remains up 6% as of Mon­day at 3:30 am ET $5.45, Block­works’ data shows. 

Upbit said any delays in reflect­ing deposits and with­drawals would depend on block pro­cess­ing sta­tus and that trans­ac­tions would pro­ceed sequen­tial­ly as blocks are completed.

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