cve/2023/CVE-2023-40021.md

19 lines
1.9 KiB
Markdown
Raw Normal View History

2024-05-25 21:48:12 +02:00
### [CVE-2023-40021](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-40021)
![](https://img.shields.io/static/v1?label=Product&message=oppia&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=%3D%20%3E%3D%201.1.0%2C%20%3C%203.3.2-hotfix-2%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-203%3A%20Observable%20Discrepancy&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-208%3A%20Observable%20Timing%20Discrepancy&color=brighgreen)
### Description
Oppia is an online learning platform. When comparing a received CSRF token against the expected token, Oppia uses the string equality operator (`==`), which is not safe against timing attacks. By repeatedly submitting invalid tokens, an attacker can brute-force the expected CSRF token character by character. Once they have recovered the token, they can then submit a forged request on behalf of a logged-in user and execute privileged actions on that user's behalf. In particular the function to validate received CSRF tokens is at `oppia.core.controllers.base.CsrfTokenManager.is_csrf_token_valid`. An attacker who can lure a logged-in Oppia user to a malicious website can perform any change on Oppia that the user is authorized to do, including changing profile information; creating, deleting, and changing explorations; etc. Note that the attacker cannot change a user's login credentials. An attack would need to complete within 1 second because every second, the time used in computing the token changes. This issue has been addressed in commit `b89bf80837` which has been included in release `3.3.2-hotfix-2`. Users are advised to upgrade. There are no known workarounds for this vulnerability.
### POC
#### Reference
- https://github.com/oppia/oppia/security/advisories/GHSA-49jp-pjc3-2532
#### Github
No PoCs found on GitHub currently.