Serious about security
Our approach to security is designed to protect buyers and sellers. We monitor every transaction from swipe to payment, we continuously innovate in fraud prevention, and we protect businesses’ data like our business depends on it—because it does. We adhere to industry-leading standards to manage our network, secure our web and client applications, and set policies across our organization.
If you believe you have discovered a security vulnerability, please follow the guidelines below.
Square recognizes the important contributions the security research community can make. We encourage coordinated reporting of security issues with our services. We take the security of our services very seriously and monitor their use for indications of a malicious attack. In order to allow us to identify legitimate security research as opposed to malicious attacks against our services, we promise not to bring legal action against researchers who:
- Share with us the full details of any problem found.
- Do not disclose the issue to others until we’ve had reasonable time to address it.
- Do not intentionally harm the experience or usefulness of the service to others.
- Never attempt to view, modify, or damage data belonging to others.
- Do not attempt a denial-of-service attack.
- Do not perform any research or testing in violation of law.
Attributes of a good report
- Detailed steps on reproducing the bug. If valuable, please include any screenshots, links you clicked on, pages visited, etc.
- Describe the versions of all relevant components of the attack (eg browser, OS, mobile app version).
- Describe a concrete attack scenario. How will the problem impact Square or Square buyers/sellers? Put the problem into context.
We welcome you to report problems under squareup.com, square.com, or cash.me. Our Android and iOS mobile applications for Square Cash and Square Register are also in scope. We are particularly interested in problems with Square’s payment flows. Confirmed vulnerabilities that directly affect our payments flows will receive a $500 minimum reward.
Special CTF-style Flags!
Find the account
We've created an account with an email address of the form
ftwr+[32 character flag]@squareup.com. Tell us how you found it, and you'll get a $1000 bounty. In case it helps, you can find the associated Square Market page here.
The SHA1 digest of the flag is:
Find the file
Find a file called
hackerone-flag.txt with the contents of the form
ftwr+[32 character flag]. Tell us how you found it, and you'll get a $1000 bounty.
The SHA1 digest of the flag is
Computing the sha1
To make sure you know that you have found the right flag, we are publishing the digests of the flags by running
echo [32 characters] | sha1sum. You can do the same on your terminal (you might need to install
sha1sum or use an alternate method).
For example, if the value of the token were
fb3f8fe63cc107c1977855c95633fb13 (it's not), then you would get:
~ echo fb3f8fe63cc107c1977855c95633fb13 | sha1sum 6f475d857588da6cc27cf38142c57fdbf4d57b9e -
Some things to keep in mind when hunting for flags:
- Only flags created by Square are eligible for the reward. There will be at most one reward per flag.
- Only the first person to report a flag and methodology for discovery will be rewarded.
- The flags are long enough that brute force won't work. You'll have to be more creative!
- Issues related to software not under Square's control
- Reports from automated tools or scans
- Social engineering of Square staff or contractors
- Any physical attempts against Square property or data centers
- Logout CSRF
- Presence of autocomplete attribute on web forms
- Missing cookie flags on non-sensitive cookies
- Missing http security headers (unless you deliver a proof of concept that leverages their absence)
- Clickjacking on widgets intended to be embedded in other pages
- Reports of insecure SSL/TLS ciphers (unless you have a working proof of concept, and not just a report from a scanner)
- An oracle that discloses whether a given username, email address, or phone number is associated with an actual account. (However, please do submit anything that allows you to recover usernames en masse.)