Headline
GHSA-qrgf-9gpc-vrxw: Bypass of CSRF protection in the presence of predictable userInfo
Description
The CSRF protection enforced by the @fastify/csrf-protection library in combination with @fastify/cookie can be bypassed from network and same-site attackers under certain conditions.
@fastify/csrf-protection supports an optional userInfo parameter that binds the CSRF token to the user. This parameter has been introduced to prevent cookie-tossing attacks as a fix for CVE-2021-29624. Whenever userInfo parameter is missing, or its value can be predicted for the target user account, network and same-site attackers can 1. fixate a _csrf cookie in the victim’s browser, and 2. forge CSRF tokens that are valid for the victim’s session. This allows attackers to bypass the CSRF protection mechanism.
As a fix, @fastify/csrf-protection starting from version 6.3.0 (and v4.1.0) includes a server-defined secret hmacKey that cryptographically binds the CSRF token to the value of the _csrf cookie and the userInfo parameter, making tokens non-spoofable by attackers. This protection is effective as long as the userInfo parameter is unique for each user.
Patches
This is patched in version 6.3.0 and v4.1.0.
Workarounds
As a workaround, developers can use a random, non-predictable userInfo parameter for each user.
Credits
- Pedro Adão (@pedromigueladao), Instituto Superior Técnico, University of Lisbon
- Marco Squarcina (@lavish), Security & Privacy Research Unit, TU Wien
Description
The CSRF protection enforced by the @fastify/csrf-protection library in combination with @fastify/cookie can be bypassed from network and same-site attackers under certain conditions.
@fastify/csrf-protection supports an optional userInfo parameter that binds the CSRF token to the user. This parameter has been introduced to prevent cookie-tossing attacks as a fix for CVE-2021-29624. Whenever userInfo parameter is missing, or its value can be predicted for the target user account, network and same-site attackers can 1. fixate a _csrf cookie in the victim’s browser, and 2. forge CSRF tokens that are valid for the victim’s session. This allows attackers to bypass the CSRF protection mechanism.
As a fix, @fastify/csrf-protection starting from version 6.3.0 (and v4.1.0) includes a server-defined secret hmacKey that cryptographically binds the CSRF token to the value of the _csrf cookie and the userInfo parameter, making tokens non-spoofable by attackers. This protection is effective as long as the userInfo parameter is unique for each user.
Patches
This is patched in version 6.3.0 and v4.1.0.
Workarounds
As a workaround, developers can use a random, non-predictable userInfo parameter for each user.
Credits
- Pedro Adão (@pedromigueladao), Instituto Superior Técnico, University of Lisbon
- Marco Squarcina (@lavish), Security & Privacy Research Unit, TU Wien
References
- GHSA-qrgf-9gpc-vrxw
- GHSA-rc4q-9m69-gqp8
- https://nvd.nist.gov/vuln/detail/CVE-2023-27495
- fastify/csrf-protection@be3e576
- https://github.com/fastify/csrf-protection/releases/tag/v4.1.0
- https://github.com/fastify/csrf-protection/releases/tag/v6.3.0
- https://www.cvedetails.com/cve/CVE-2021-29624
Related news
@fastify/csrf-protection is a plugin which helps protect Fastify servers against CSRF attacks. The CSRF protection enforced by the @fastify/csrf-protection library in combination with @fastify/cookie can be bypassed from network and same-site attackers under certain conditions. @fastify/csrf-protection supports an optional userInfo parameter that binds the CSRF token to the user. This parameter has been introduced to prevent cookie-tossing attacks as a fix for CVE-2021-29624. Whenever userInfo parameter is missing, or its value can be predicted for the target user account, network and same-site attackers can 1. fixate a _csrf cookie in the victim's browser, and 2. forge CSRF tokens that are valid for the victim's session. This allows attackers to bypass the CSRF protection mechanism. As a fix, @fastify/csrf-protection starting from version 6.3.0 (and v4.1.0) includes a server-defined secret hmacKey that cryptographically binds the CSRF token to the value of the _csrf cookie and the use...