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Python regurgitates Dropbox secrets to boffins

Researchers pick over the entrails to spot vulns

A couple of security researchers have set spines shivering in the cloud world by demonstrating that Dropbox's obfuscated code can be reverse-engineered, along the way capturing SSL data from the service's cloud and bypassing the two-factor authentication used to secure user data.

However, as is clear from the Usenix research paper and has been confirmed by Dropbox, their work doesn't create a generic attack vector. The attacks only work if the attacker already has unfettered access to the target machine.

As Dropbox puts it: “In the case outlined here, the user’s computer would first need to have been compromised in such a way that it would leave the entire computer, not just the user's Dropbox, open to attacks across the board.” (More on this in a minute.)

Perhaps the most interesting aspect of the work by Openwall's Dhiro Kholia and CodePainters' Przemyslaw Wegrzyn is that they were able to reverse-engineer the heavily protected Dropbox Python code.

“Our work reveals the internal API used by Dropbox client and makes it straightforward to write a portable open-source Dropbox client,” they write. As a result, they say, it should be possible for researchers to subject Dropbox to more rigorous security analysis.

The researchers also observe that Dropbox's two-factor authentication, used for accessing its Website, is not supported in the client software. “This implies that it is sufficient to have only the host_id value to gain access to the target’s data stored in Dropbox.”

However, the host_id value is stored on the local machine in an encrypted SQLite database – meaning it can only be recovered by someone with access to that machine. ®

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