Preventing cross-site attacks using same-site cookies

Our comms team told us we need an image; our legal team told us it needed to be freely licensed. Credit: Carsten Schertzer (Creative Commons Attribution 2.0)


Dropbox employs traditional cross-site attack defenses, but we also employ same-site cookies as a defense in depth on newer browsers. In this post, we describe how we rolled out same-site cookie based defenses on Dropbox, and offer some guidelines on how you can do the same on your website.


Recently, the IETF released a new RFC introducing same-site cookies.

Read more

DropboxMacUpdate: Making automatic updates on macOS safer and more reliable

Keeping users on the latest version of the Dropbox desktop app is critical. It allows our developers to rapidly innovate, showcase new features to our users, maintain compatibility with server endpoints, and mitigate risk of incompatibilities that may creep in with platform/OS changes.

Our auto-update system, as originally designed, was written as a feature of the desktop client. Basically, as part of regular file syncing, the server can send down an entry in the metadata that says, “Please update to version X with checksum Y.” The client would then download the file, verify the checksum, open the payload,

Read more

Introducing Stormcrow

A SaaS company like Dropbox needs to update our systems constantly, at all levels of the stack. When it comes time to tune some piece of infrastructure, roll out a new feature, or set up an A/B test, it’s important that we can make changes and have them hit production fast.

Making a change to our code and then “simply” pushing it is not an option: completing a push to our web servers can take hours, and shipping a new mobile or desktop platform release takes even longer. In any case, a full code deployment can be dangerous because it could introduce new bugs: what we really want is a way to put some configurable “knobs” into our products,

Read more

Meet Securitybot: Open Sourcing Automated Security at Scale

Security incidents happen. And when they do, they need to be dealt with—quickly. That’s where detection comes into play. The faster incidents are detected, the faster they can be handed off to the security team and resolved. To make detection as fast as possible, teams are usually aided by monitoring infrastructure that fires off an alert any time something even slightly questionable occurs. These alerts can lead to a deluge of information, making it difficult for engineers to sift through. Even worse, a large number of these alerts are false positives, caused by engineers arbitrarily running sudo -i or nmap.

Read more

How Dropbox securely stores your passwords

It’s universally acknowledged that it’s a bad idea to store plain-text passwords. If a database containing plain-text passwords is compromised, user accounts are in immediate danger. For this reason, as early as 1976, the industry standardized on storing passwords using secure, one-way hashing mechanisms (starting with Unix Crypt). Unfortunately, while this prevents the direct reading of passwords in case of a compromise, all hashing mechanisms necessarily allow attackers to brute force the hash offline, by going through lists of possible passwords, hashing them, and comparing the result. In this context, secure hashing functions like SHA have a critical flaw for password hashing: they are designed to be fast.

Read more