Microsoft says it’s investigating claims that its GitHub account has been hacked, and while some say the leaked files appear to be legitimate, it’s unlikely that they contain any sensitive information.
Data breach monitoring and prevention service Under the Breach reported on Thursday that a hacker claimed to have obtained 500 GB of source code from Microsoft’s private GitHub repositories. Under the Breach said it had conducted some research and determined that the files were likely legitimate. Screenshots posted by the service suggest that the files were likely obtained on March 28.
A post offering some of the files for free on a hacker forum claims that the data is 54 GB compressed and 500 GB uncompressed, but software engineer Rafael Rivera, who also confirmed that the files appear to be real, said there are only roughly 63 GB of files when uncompressed.
The leaked data includes source code for Azure, Office, and some Windows runtime files and APIs, Under the Breach said, adding that while the leaked files did not appear to include anything sensitive they could hold keys and passwords left by mistake in the code.
However, Dustin Metzgar, a software engineer who in the past worked for Microsoft for nearly a decade, said the code is unlikely to contain such data as the tech giant puts a lot of effort into ensuring that secrets are removed from source code.
“They have check-in gates and routine scans for anything that looks like a secret. All certs and secrets are rotated as well. Nothing is foolproof but they make a real effort,” Metzgar said on Twitter.
A Microsoft spokesperson told SecurityWeek that the company is aware of the claims and has launched an investigation, but did not provide any additional information. A Microsoft employee initially responded to Under the Breach’s Twitter post, saying the leak was fake, but later removed their tweet.
It’s worth noting that Microsoft owns GitHub.
Twitter user Nirmal Guru also says the leaked source code appears to be real, but points out that it’s “useless” as all private Microsoft repositories on GitHub are made public at some point.
Under the Breach reported that the individual responsible for this hack recently also leaked 15 million records stolen from Indonesian e-commerce company Tokopedia.
Related: Gentoo Publishes Incident Report After GitHub Hack
Related: Canonical GitHub Account Hijacked

Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.
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