Hackers don't even need your password anymore to get access to your cloud data.
Newly published research, released at the Black Hat conference in Las Vegas on Wednesday by security firm Imperva, shows how a "man-in-the-cloud" attack can grab cloud-based files -- as well as infecting users with malware -- without users even noticing.
The attack differs from traditional man-in-the-middle attacks, which rely on tapping data in transit between two servers or users, because it exploits a vulnerability in the design of many file synchronization offerings, including Google, Box, Microsoft, and Dropbox services. This is not just an issue for consumers, but also businesses, which increasingly use cloud-based services to share sensitive customer and corporate data.
The report by Imperva, which has a research unit as well as having a commercial stake in the security space, said in some cases "recovery of the account from this type of compromise is not always feasible."
The attack works by grabbing the password token, a small file that sits on a user's devices for convenience (which saves the user from entering their password each time). When the token is obtained, either through a phishing attack or a drive-by exploit, it can be used to fool a new machine into thinking the attacker is the account's owner. From there, the attacker can access and steal files, and even add malware or ransomware (which is on the rise) to the victim's cloud folder, which can be used for further attacks.
Making matters worse, account owners are almost powerless. Because the tokens are tied to the user's device, changing the account password would not lock out the attacker.