CVE-2023-40021

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Summary

CVECVE-2023-40021
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2023-08-16 21:15:00 UTC
Updated2023-08-25 20:08:00 UTC
DescriptionOppia 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.

Risk And Classification

Problem Types: CWE-203

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Oppia Oppia All All All All
Application Oppia Oppia 3.3.2 - All All

References

ReferenceSourceLinkTags
Fix GHSA-49jp-pjc3-2532: Strengthen CSRF Protections (#18769) · oppia/oppia@b89bf80 · GitHub MISC github.com
Fix GHSA-49jp-pjc3-2532: Strengthen CSRF Protections by U8NWXD · Pull Request #18769 · oppia/oppia · GitHub MISC github.com
github.com/oppia/oppia/blob/3a05c3558a292f3db9e658e60e708c266c003fd0/cor... MISC github.com
CVE-2023-40021: Timing Attack Reveals CSRF Tokens · Advisory · oppia/oppia · GitHub MISC github.com
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