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Strapi plugins vulnerable to Server-Side Template Injection and Remote Code Execution in the Users-Permissions Plugin

Critical severity GitHub Reviewed Published Apr 18, 2023 in strapi/strapi • Updated Nov 7, 2023

Package

npm @strapi/plugin-email (npm)

Affected versions

< 4.5.6

Patched versions

4.5.6
npm @strapi/plugin-users-permissions (npm)
< 4.5.6
4.5.6

Description

Summary

Strapi through 4.5.5 allows authenticated Server-Side Template Injection (SSTI) that can be exploited to execute arbitrary code on the server.

Details

Strapi through 4.5.5 allows authenticated Server-Side Template Injection (SSTI) that can be exploited to execute arbitrary code on the server. A remote attacker with access to the Strapi admin panel can inject a crafted payload that executes code on the server into an email template that bypasses the validation checks that should prevent code execution.

IoC

Using just the request log files, the only IoC to search for is a PUT request to URL path /users-permissions/email-templates. This IoC only indicates that a Strapi email template was modified on your server and by itself does not indicate if your Strapi server has been compromised. If this IoC is detected, you will need to manually review your email templates on your Strapi server and backups of your database to see if any of the templates contain a lodash template delimiter (eg. <%STUFF HERE%>) that contains suspicious JavaScript code. Generally speaking these templates should look like the following, you may have minor adjustments but any unrecognized code should be considered suspicious.

Reset Password Template:

<p>We heard that you lost your password. Sorry about that!</p>

<p>But don’t worry! You can use the following link to reset your password:</p>
<p><%= URL %>?code=<%= TOKEN %></p>

<p>Thanks.</p>

Email Confirmation Template:

<p>Thank you for registering!</p>

<p>You have to confirm your email address. Please click on the link below.</p>

<p><%= URL %>?confirmation=<%= CODE %></p>

<p>Thanks.</p>

Specifically you should look for odd code contained within the <%STUFF HERE%> blocks as this is what is used to bypass the lodash templating system. If you find any code that is not a variable name, or a variable name that is not defined in the template you are most likely impacted and should take immediate steps to confirm there are no malicious applications running on your servers.

Impact

All users on Strapi below 4.5.6 with access to the admin panel and the ability to modify the email templates

References

@alexandrebodin alexandrebodin published to strapi/strapi Apr 18, 2023
Published by the National Vulnerability Database Apr 19, 2023
Published to the GitHub Advisory Database Apr 19, 2023
Reviewed Apr 19, 2023
Last updated Nov 7, 2023

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS score

61.428%
(98th percentile)

Weaknesses

CVE ID

CVE-2023-22621

GHSA ID

GHSA-2h87-4q2w-v4hf

Source code

Credits

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