The paper was released by Openwall's Dhiru Kholia and Code Painters' Przemyslaw Wegrzyn and details techniques to sneak past Dropbox's two-factor authentication to intercept SSL data from the company's servers. The two researchers claim to have discovered the exploit by reverse engineering Dropbox's source code.
"We show how to unpack, decrypt and decompile Dropbox from scratch and in full detail. This paper presents new and generic techniques to reverse engineer frozen Python applications," wrote Kholia and Przemyslaw.
The pair claim to have bypassed Dropbox's security using a custom-built, open-source Dropbox client. They said the technique is fairly basic but dangerous as, if misused, hackers can steal data from Dropbox and hijack unwary users' accounts.
"Our work uses various code-injection techniques and monkey-patching to intercept SSL data in [the] Dropbox client. We have used these techniques successfully to snoop on SSL data in other commercial products as well," read the paper.
Last year Dropbox was forced to add two-factor authentication after millions of its users were spammed following a successful cyber attack on its systems.
A Dropbox spokesperson told to V3 the company is aware of the research, but downplayed its significance, clarifying the exploit only works if the user's main machine is already compromised.
"We appreciate the contributions of these researchers and everyone who helps keep Dropbox safe. However, we believe this research does not present a vulnerability in the Dropbox client. 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," said the spokesperson.
The paper added: "We hope that our work inspires the security community to write an open-source Dropbox client, reﬁne the techniques presented in this paper and conduct research into other cloud-based storage systems."
Kholia and Wegrzyn are two of many to publicly publish exploits on big-name services and technologies in recent weeks. Renowned hackers Charlie Miller and Chris Valasek released tools capable of hijacking control of moving cars to the general public at the Defcon expo in Las Vegas at the beginning of August.