usd-2019-0018 | Bitbucket/v5.10.1

Description

Advisory ID: usd-2019-0018
CVE Number: N/A
Affected Product: Bitbucket
Affected Version: v5.10.1
Vulnerability Type: User Enumeration
Security Risk: Low
Vendor URL: https://www.atlassian.com
Vendor Status: Not fixed

User enumeration is when a malicious actor can use brute-force to either guess or confirm valid users in a system. User enumeration is often a web application vulnerability, though it can also be found in any system that requires user authentication. The malicious actor is looking for differences in the server’s response based on the validity of submitted credentials.

Proof of Concept

Unprivileged users are able to enumerate valid usernames. Hereto, an user sends a request to „/admin/permissions/users“ with following request

GET-Parameter "?permission=LICENSED_USER&name=".

If the username exists, the server responds with an error message that the user has unsufficient rights for this process.
If the username does not exists, the server responds with a message that the user does not exists.

Fix

Even if the user doesn’t exists, the server should respond with an error message which points out that the user doesn’t have sufficient rights to execute the process.

Timeline

  • 2019-03-28 Vulnerability securily submitted to security@atlassian.com
  • 2019-04-11 Second contact attempt via contact formular
  • 2019-05-23 Atlassian Security Team agreed with the publishment of the advisory
  • 2019-07-31 Security advisory released

Credits

This security vulnerabilities were found by Tobias Neitzel and Julian Frey of usd AG.

ABOUT usd SECURITY ADVISORIES

In order to protect businesses against hackers and criminals, we always have to keep our skills and knowledge up to date. Thus, security research is just as important for our work as is building up a security community to promote the exchange of knowledge. After all, more security can only be achieved if many individuals take on the task.

Our CST Academy and our usd HeroLab are essential parts of our security mission. We share the knowledge we gain in our practical work and our research through training courses and publications. In this context, the usd HeroLab publishes a series of papers on new vulnerabilities and current security issues.

Always for the sake of our mission: „more security.“

to usd AG


In accordance with usd AG’s Responsible Disclosure Policy, all vendors have been notified of the existence of these vulnerabilities.

Disclaimer

The information provided in this security advisory is provided „as is“ and without warranty of any kind. Details of this security advisory may be updated in order to provide as accurate information as possible.