CSRF Token Forgery in Adminer via XOR Weakness

Executive Summary

Adminer before version 5.4.3 has a flawed CSRF token scheme that transmits both the XOR mask and masked value in every token. This allows an attacker who observes a single token to recover the session secret with a simple XOR operation and forge unlimited valid tokens. The token also has low entropy (~20 bits), making brute-force attacks possible. The vulnerability enables cross-site request forgery against authenticated sessions, allowing arbitrary SQL execution.

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Detection Guidance

To detect this vulnerability, monitor network traffic for Adminer instances using the flawed CSRF token scheme. Look for tokens formatted as (rand XOR secret):rand in requests. Check Adminer version; versions <= 5.4.3-dev are vulnerable. Inspect logs for repeated failed CSRF token validations or unusual SQL query execution patterns.

• Check Adminer version: grep -r "Adminer" /var/www/ or similar paths to find version info.
• Monitor network traffic: Use tcpdump or Wireshark to capture HTTP requests to Adminer and inspect CSRF tokens for the vulnerable format.
• Inspect logs: Look for repeated failed CSRF token validations or unexpected SQL queries in web server or Adminer logs.

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Impact Analysis

An attacker could exploit this to perform CSRF attacks on your authenticated Adminer sessions. This could allow them to execute arbitrary SQL commands, such as deleting tables, stealing data, or creating backdoor users, all while impersonating you. The attack could be triggered by visiting a malicious webpage.

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Compliance Impact

This vulnerability could lead to unauthorized data access, modification, or deletion, violating GDPR's integrity and confidentiality requirements and HIPAA's safeguards for protected health information. Compliance failures may result in legal penalties, reputational damage, and loss of trust.

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Mitigation Strategies

Immediately upgrade Adminer to version 5.4.3 or later to address the CSRF token flaw. If upgrading is not possible, disable Adminer or restrict access to trusted networks. Implement additional CSRF protections like stricter token validation or rate limiting to mitigate brute-force risks.

• Upgrade Adminer: Download and install Adminer 5.4.3 or newer from the official repository.
• Restrict access: Use firewalls or network policies to limit Adminer access to authorized users only.
• Monitor activity: Increase monitoring for suspicious SQL queries or unauthorized access attempts post-upgrade.

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