From what I’ve been reading, it sounds like they were malicious from the very beginning. The work to integrate the malware goes back to 2021. https://boehs.org/node/everything-i-know-about-the-xz-backdoor
It’s an extremely sophisticated attack that was hidden very well, and was only accidentally discovered by someone who noticed that rejected SSH connections (eg invalid key or password) were using more CPU power and taking 0.5s longer than they should have. https://mastodon.social/@AndresFreundTec/112180406142695845
From that post, commits set to UTC+0800 and activity between UTC 12-17 indicate that the programmer wasn’t operating from California but from another country starting with C. The name is also another hint.
That could be part of their plan though… Make people think they’re from China when in reality they’re a state-sponsored actor from a different country. Hard to tell at this point. The scary thing is they got very close to sneaking this malware in undetected.
A lot of critical projects are only maintained by one person who may end up burning out, so I’m surprised we haven’t seen more attacks like this. Gain the trust of the maintainer (maybe fix some bugs, reply to some mailing-list posts, etc), take over maintenance, and slowly add some malware one small piece at a time, interspersed with enough legit commits that you become one of the top contributors (and thus people start implicitly trusting you).
Edit: Based on this analysis, they may have been based in a European timezone and just changed their timezone to UTC+8 before committing to Git to make it look like they were in China: https://rheaeve.substack.com/p/xz-backdoor-times-damned-times-and. Their commits were usually between 9 am and 6 pm Eastern European Time, and there are a few commits where the timezone was set to UTC+2 instead of UTC+8.
According to this post, the person involved exposed a different name at one point.
https://boehs.org/node/everything-i-know-about-the-xz-backdoor
Cheong is not a Pingyin name. It uses Romanization instead. Assuming that this isn’t a false trail (unlikely, why would you expose a fake name once instead of using it all the time?) that cuts out China (Mainland) and Singapore which use the Pingyin system. Or somebody has a time machine and grabbed this guy before 1956.
Likely sources of the name would be a country/Chinese administrative zone that uses Chinese and Romanization. Which gives us Taiwan, Macau, or Hong Kong, all of which are in GMT+8. Note that two of these are technically under PRC control.
Realistically I feel this is just a rogue attacker instead of a nation state. The probability of China 1. Hiring someone from these specific regions 2. Exposing a non-pinying full name once on purpose is extremely low. Why bother with this when you have plenty of graduates from Tsinghua in Beijing? Especially after so many people desperate for jobs after COVID.
