Date discovered: February 2024
Severity: Critical
Affected product: Microsoft Entra ID (Azure AD) Jira SSO Plugin
Attack type: Elevation of Privilege (EoP)

Introduction

In early 2024, a critical security vulnerability was discovered in the Microsoft Entra Jira Single-Sign-On (SSO) plugin—a tool used to allow users to log into Atlassian Jira using their Microsoft Entra ID (formerly Azure Active Directory) credentials. Identified as CVE-2024-21401, this exploit can allow attackers to escalate their privileges within Jira instances, potentially giving them unauthorized administrative access.

If your organization uses Jira with Microsoft Entra (Azure AD) for single sign-on, read on to understand the risk, the technical details, and what can be done about it.

What is CVE-2024-21401?

In simple terms, this vulnerability allows an attacker to "trick" the Jira SSO plugin, gaining permissions and roles in Jira that they should never have. The flaw was found in how the plugin verifies SAML assertions (the bits of data it receives from Entra ID saying, "This user has logged in").

Assign themselves privileges

- Access or modify sensitive Jira issues/tickets

Why is this bad?
If someone can pretend to be an admin, they can change project settings, view private issues, or even disrupt your entire Jira setup.

You have installed the Microsoft Entra (Azure AD) SSO plugin to integrate SSO functionality

Cloud (Jira Cloud) users are NOT affected by this specific vulnerability.

How Does the Exploit Work?

The heart of the issue lies in how the Entra Jira SSO plugin validates SAML assertions.

Confirm that it hasn’t been tampered with

3. Map the incoming user/email to a matching Jira account and assign proper roles

The problem:
The plugin had a bug in its SAML validation logic and user mapping. It failed to properly check the user's email or username against the incoming assertion values. With crafted SAML assertions, an attacker could impersonate other Jira users, even admins.

Step-by-Step Attack Flow

1. Intercept/Modify the SAML assertion being sent from Microsoft Entra to Jira (via network access, a malicious proxy, or by controlling an IdP).

Example Exploit Code

Here is a simplified Python snippet using python3-saml that demonstrates how an attacker might construct a malicious SAML response:

# WARNING: EDUCATIONAL USE ONLY

from onelogin.saml2.utils import OneLogin_Saml2_Utils

# Example SAML assertion template
saml_assertion = """
<saml:Assertion ...>
  ...
  <saml:AttributeStatement>
    <saml:Attribute Name="email">
      <saml:AttributeValue>admin@example.com</saml:AttributeValue>
    </saml:Attribute>
    <saml:Attribute Name="username">
      <saml:AttributeValue>jira-admin</saml:AttributeValue>
    </saml:Attribute>
  </saml:AttributeStatement>
  ...
</saml:Assertion>
"""

# Attacker modifies the assertion to impersonate an admin
# Then signs and delivers it to the Jira SSO endpoint

> Note: In real scenarios, attackers could automate this process, using tools like Burp Suite or custom scripts, especially if they control the SAML Identity Provider (IdP) or can MITM the SSO flow.

References and Original Advisories

- Microsoft Security Advisory
- Atlassian Security Bulletin
- NVD Entry for CVE-2024-21401
- SAML Exploitation Write-up

What Should You Do?

1. Patch Immediately
Microsoft and Atlassian have released updates for the affected plugin. Update to the latest version as soon as possible.

2. Review Audit Logs
Check Jira and Entra logs for any suspicious logins, especially those involving admin accounts or failed assertion validations.

3. Limit SSO IDP Control
Ensure your SAML IdP endpoints are not exposed or under the control of untrusted parties.

4. Harden Network Access
Limit direct access to Jira SSO endpoints where possible, and use network-level protections.

Conclusion

CVE-2024-21401 is a critical elevation of privilege vulnerability affecting organizations that use Microsoft Entra Jira Single-Sign-On integration. If left unpatched, attackers could escalate to full admin rights in Jira.

Don't wait:

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*If you want to learn more about SAML vulnerabilities, check out this hands-on SAML attack lab*.

Timeline

Published on: 02/13/2024 18:15:58 UTC
Last modified on: 02/23/2024 21:06:05 UTC