BNHS Incident Response: Broken Auth to RCE Exploitation Chain

A comprehensive incident response engagement involving the analysis and remediation of a sophisticated attack chain that exploited broken authentication to achieve remote code execution (RCE) and establish persistent backdoor access.

Project Overview

This incident response project involved investigating and remediating a complex security breach that leveraged broken authentication mechanisms to establish a complete exploitation chain, resulting in:

  • Remote code execution (RCE) on production servers
  • Web shell deployment and persistent backdoor access
  • SEO spam injection campaigns
  • Malicious code injection across multiple applications

Technical Challenge

The incident involved multiple web applications built on different frameworks:

  • Laravel applications with authentication bypasses
  • WordPress sites with compromised admin access
  • CodeIgniter applications vulnerable to injection attacks

Investigation & Analysis

1. Initial Assessment

  • Conducted forensic analysis of compromised systems
  • Identified attack vectors and entry points
  • Mapped the complete exploitation chain from initial access to persistence

2. Backdoor Analysis

  • Obfuscated PHP Backdoor Reverse Engineering
    • Analyzed heavily obfuscated PHP backdoors deployed across multiple applications
    • Reverse engineered obfuscation techniques to understand payload functionality
    • Identified command and control (C2) communication patterns
    • Documented backdoor persistence mechanisms

3. Malicious Code Injection Analysis

  • SEO Spam Campaign Investigation
    • Analyzed injected SEO spam content targeting search engine rankings
    • Identified injection points in database and file system
    • Tracked malicious content propagation across affected sites
    • Documented impact on search engine indexing

Technical Implementation

Attack Chain Reconstruction

# Initial broken authentication exploitation
1. Authentication bypass in Laravel application
2. Privilege escalation to admin access
3. File upload vulnerability exploitation
4. PHP web shell deployment
5. Post-exploitation persistence establishment

Backdoor Analysis Tools

# Custom PHP deobfuscation script
def deobfuscate_php_backdoor(obfuscated_code):
    # Remove base64 encoding layers
    # Decode hex-encoded strings
    # Analyze eval() and system() calls
    # Extract C2 communication protocols

Remediation Process

# Server hardening checklist
1. Remove all identified backdoors and web shells
2. Patch authentication vulnerabilities
3. Implement file upload restrictions
4. Update all application frameworks
5. Deploy additional monitoring and detection rules

Key Achievements

Security Improvements

  • Complete Backdoor Removal: Successfully identified and removed all backdoor files and database entries
  • Vulnerability Patching: Fixed all authentication and authorization vulnerabilities across multiple applications
  • Server Hardening: Implemented comprehensive security controls to prevent reinfection

Technical Deliverables

  • Detailed Incident Report: Comprehensive documentation of attack timeline, methods, and impact
  • Custom Analysis Tools: Developed specialized scripts for PHP backdoor deobfuscation
  • Hardening Guidelines: Created security implementation guidelines for the organization

Skills Demonstrated

Technical Expertise

  • Incident Response: End-to-end incident handling from detection to recovery
  • Malware Analysis: Reverse engineering of obfuscated PHP backdoors
  • Forensic Investigation: Digital forensics techniques for attack reconstruction
  • Multiple Framework Knowledge: Laravel, WordPress, CodeIgniter security assessment

Security Tools Used

  • Static Analysis: PHP code analysis for backdoor detection
  • Dynamic Analysis: Runtime analysis of malicious code execution
  • File System Forensics: Analysis of compromised files and directories
  • Database Forensics: Investigation of injected malicious content

Impact & Results

Security Posture Improvement

  • 100% Backdoor Elimination: All malicious code successfully removed
  • Vulnerability Coverage: Complete patching of identified security flaws
  • Monitoring Enhancement: Improved detection capabilities for future incidents

Business Continuity

  • Minimal Downtime: Maintained service availability during remediation
  • Data Integrity: Preserved legitimate data while removing malicious content
  • Reputation Protection: Prevented further SEO damage and search ranking issues

Technical Challenges Overcome

Obfuscation Analysis

  • Successfully reverse engineered multi-layer PHP obfuscation
  • Developed automated deobfuscation tools for similar future incidents
  • Created signatures for backdoor detection across file systems

Multi-Application Environment

  • Coordinated remediation across different application frameworks
  • Ensured consistent security implementation across diverse technology stack
  • Maintained application functionality while implementing security fixes

This project demonstrates comprehensive incident response capabilities, including advanced malware analysis, multi-platform security assessment, and effective remediation strategies in complex enterprise environments.