Binance CSO unwittingly foreshadowed $6.3B hack tactic months before attack

Months before Binance lost $6.3 billion to a hack, its chief security officer described to Cointelegraph how a fake job interview could give attackers a foothold inside the exchange — closely resembling one of the entry methods later used against the exchange.

During a July interview about Binance’s response to rising security threats, Jimmy Su told Cointelegraph that fake job interviews were “something we worry about a lot internally,” explaining how attackers could tailor a job opportunity to an employee before persuading them to run code as part of a technical assessment.

“And once that gets executed, the device is compromised and then they can start harvesting credentials,” Su said, adding that attackers could then use that to penetrate further into the network.

Su’s detailed warning about malicious coding assessments was not included in Cointelegraph’s July coverage, but takes on new significance following the biggest crypto exchange hack in history.

In September, a Binance software engineer downloaded a malicious coding assignment onto his work computer during a fake job interview. That compromise became part of the multistage attack that culminated in October’s theft, according to Binance’s preliminary investigation.

During the interview with Cointelegraph, Su had also anticipated why security tools might miss such a trap. A technical assessment could involve seemingly legitimate steps, such as downloading a code repository from GitHub, he explained in July.

“Each step is actually legitimate on its own. So a lot of the anti-virus tools may not be able to detect it and flag it,” he said.

Binance’s investigation subsequently described a similar detection failure, saying the assignment’s setup process executed malware that evaded its endpoint security tools through obfuscation and other evasion techniques.

Binance said onus is on the company to detect attacks

Su told Cointelegraph that it was Binance’s responsibility to contain the risk when employees pursued outside opportunities on work computers.

“Of course employees can explore outside opportunities. What we do worry about is that they do so on the company device,” he said. If an employee fell for a fake interview, he added, “the onus is on us to detect it,” and to “stop the actual execution of that code.”