We finally have more info about how exactly Microsoft was hacked by Chinese threat actors. It’s a doozy, so strap in.
Back in June, hacking group Storm-0558 accessed the cloud-based Outlook email systems for 25 organizations, including at least two US government agencies. We finally know how they managed to pull it off.
The hackers got their hands on a Microsoft account consumer signing key, all the way back in 2021. This cryptographic key is used to generate authentication ‘tokens’ that prove a user’s identity before they’re allowed to access data and services. This is usually stored in a highly isolated and restricted ‘production environment.’
However, during an April 2021 consumer signing system crash, the signing key made its way out of this secure environment and into a crash dump, which should not happen under normal circumstances. A race condition allowed the key to be present in the crash dump, which Microsoft did not know at the time, and this mass of data was subsequently moved from the isolated production network into the company’s debugging environment on the internet-connected corporate network.
At some point after this, Storm-0558 successfully compromised a Microsoft engineer’s corporate account, which had access to the debugging environment containing the crash dump, and subsequently the signing key.
@Microsoft’s explanation covers this whole controversy, and the company has since patched the accumulation of errors and issues that led to this, but the one missing link is how the threat actors got their hands on this engineer’s account.
As my good friend Jacob Williams put it in the article below, “All the best hacks are deaths by 1,000 paper cuts, not something where you exploit a single vulnerability and then get all the goods.”
Indeed, the best threat actors are cunning, patient and perseverent - so much so that they can infiltrate global corporations.
Here’s the news story:
wired.com/story/china-backed…
Microsoft’s post-mortem report on the attack:
msrc.microsoft.com/blog/2023…