Tech Stack

• Affected Technology: Apache Shiro

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Date(s) Issued

• Publication Date: July 13, 2016
• Last Modified Date: N/A (pending reanalysis)

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Criticality

• CVSS Score: Pending reanalysis by NVD (Critical impact likely based on arbitrary code execution potential).

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Overview

CVE-2016-4437 is a critical vulnerability in Apache Shiro prior to version 1.2.5. If the cipher key for the “remember me” feature is not explicitly configured, it uses a default key. This vulnerability allows remote attackers to exploit a request parameter to execute arbitrary code or bypass access controls.

Affected versions:

• Apache Shiro versions prior to 1.2.5

Potential impacts:

• Arbitrary code execution.
• Access control bypass, allowing unauthorized access to protected resources.

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Solution/Mitigation

1. Upgrade Apache Shiro
   • Upgrade to Apache Shiro version 1.2.5 or newer. This release ensures that the “remember me” feature enforces explicit key configuration and mitigates the vulnerability.
   • Use the official Apache Shiro download page to get the latest version.
2. Configure a Secure Cipher Key
   • If upgrading is not immediately possible, configure a secure and unique cipher key for the “remember me” feature in your Shiro application configuration file.
   Example configuration in shiro.ini:propertiesCopy coderememberMe.cookie.encryptionCipherKey=YOUR_SECURE_KEY_HERE
   • Generate a strong encryption key using a secure random number generator or tools like OpenSSL.
3. Restrict External Access
   • Limit external access to your application to reduce exposure to potential attackers, especially for endpoints utilizing the “remember me” feature.
4. Apply Input Validation
   • Ensure that request parameters are validated to prevent exploitation through malicious input.
5. Monitor and Audit
   • Regularly review server and application logs for unusual or unauthorized activities.
   • Use security monitoring tools to detect and block suspicious request patterns.

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Confirmation & Additional Information

Verification:

Confirm the Shiro version after upgrading using your build tool or application runtime logs.

Test the “remember me” functionality to ensure it works correctly with the configured cipher key.

Staying Updated:

Subscribe to the Apache Shiro mailing list for announcements and security updates.

Periodically review Apache Shiro Security Advisories.

Additional Resources:

National Vulnerability Database: CVE-2016-4437

Apache Shiro Documentation: Configuring Remember Me