WidePepper Malware Analysis: Dissecting the Implant

Sample Information

WidePepper implant represents a highly sophisticated malware specimen designed for long-term persistence and data exfiltration. This analysis provides a comprehensive examination of its architecture, functionality, and evasion techniques.

File Analysis

Basic Properties

• Filename: update_service.dll
• File Size: 2,147,456 bytes (2.05 MB)
• MD5 Hash: e4d909c290d0fb1ca068ffaddf22cbd0
• SHA256 Hash: 4a7b8c9d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3
• Compilation Timestamp: 2024-10-15 09:30:42 UTC
• Compiler: Microsoft Visual Studio 2022 (C++)

PE Structure Analysis

PE Header:
- Machine: x64
- Number of Sections: 8
- Entry Point: 0x0000A000
- Image Base: 0x10000000

Sections:
- .text: 0x00001000 - 0x0008A000 (Executable code)
- .rdata: 0x0008A000 - 0x0009F000 (Read-only data)
- .data: 0x0009F000 - 0x000A5000 (Initialized data)
- .rsrc: 0x000A5000 - 0x000B2000 (Resources)
- .reloc: 0x000B2000 - 0x000B8000 (Relocations)
- .widepepper: 0x000B8000 - 0x00100000 (Custom encrypted section)

Behavioral Analysis

Installation Process

1. DLL Injection: Loaded into legitimate process (svchost.exe)
2. Registry Persistence: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
3. Service Creation: “Windows Update Service” with elevated privileges
4. Firewall Bypass: Modification of Windows Firewall rules

Runtime Behavior

• Memory Residency: Operates entirely in memory to avoid disk artifacts
• Process Injection: Migrates between processes for anti-analysis
• Network Communications: Encrypted C2 beaconing every 10 minutes
• Data Collection: Comprehensive system and user monitoring

Code Analysis

Main Components

Configuration Module

 1struct WidePepperConfig {
 2    char c2_domain[256];
 3    uint16_t c2_port;
 4    char encryption_key[32];
 5    uint32_t beacon_interval;
 6    char victim_id[16];
 7    bool enable_keylogger;
 8    bool enable_screenshot;
 9    char exfil_path[512];
10};

Communication Module

The implant uses a custom protocol for C2 communications:

Packet Structure:
+-------------------+
| Magic (4 bytes)   | 0x57494445 ("WIDE")
+-------------------+
| Version (2 bytes) | Protocol version
+-------------------+
| Command (2 bytes) | Operation type
+-------------------+
| Length (4 bytes)  | Payload size
+-------------------+
| Payload (variable)| Encrypted data
+-------------------+

Encryption Implementation

WidePepper employs AES-256 in CBC mode with custom key derivation:

1void derive_key(const char* password, unsigned char* key) {
2    PKCS5_PBKDF2_HMAC(password, strlen(password),
3                     salt, sizeof(salt), 10000,
4                     EVP_sha256(), 32, key);
5}

Anti-Analysis Techniques

Anti-Debugging

• PEB Manipulation: Checks BeingDebugged flag
• Hardware Breakpoints: Detects and removes debug registers
• Timing Attacks: Measures execution time for debugger detection
• Exception Handling: Catches debug events and alters behavior

Anti-VM

• Registry Checks: Scans for VMware/Hyper-V artifacts
• MAC Address Analysis: Identifies virtual network adapters
• CPU Instructions: Uses SIDT/SGDT for virtualization detection
• Process Enumeration: Detects VM tools and services

Obfuscation Methods

• String Encryption: Runtime decryption of sensitive strings
• Control Flow Flattening: Obfuscated execution flow
• Junk Code Insertion: Meaningless instructions to confuse analysis
• Dynamic API Resolution: LoadLibrary/GetProcAddress for imports

Functionality Deep Dive

Data Collection Capabilities

System Information

• Hardware Inventory: CPU, memory, storage, and network details
• Software Inventory: Installed applications and versions
• User Accounts: Local and domain user information
• Network Configuration: IP addresses, routes, and firewall rules

User Activity Monitoring

• Keystroke Logging: Capture of all keyboard input
• Screenshot Capture: Periodic desktop screenshots
• Clipboard Monitoring: Interception of copy/paste operations
• File Access Tracking: Monitoring of sensitive file operations

Command Execution

The implant supports various C2 commands:

Data Exfiltration

• Chunked Transfers: Large files split into 1MB segments
• Compression: LZMA compression for bandwidth efficiency
• Encryption: AES-256 encryption of all exfiltrated data
• Steganography: Data hiding in legitimate network traffic

Network Communications

Beaconing Pattern

• Interval: 10 minutes ± 2 minutes (jittered)
• Protocol: HTTPS POST to /beacon endpoint
• User-Agent: “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36”
• Content-Type: application/octet-stream

C2 Commands

Commands are received via the same HTTPS channel:

• Authentication: HMAC-SHA256 signature verification
• Decryption: AES-256 decryption of command payload
• Execution: Asynchronous command processing
• Response: Encrypted acknowledgment and results

Persistence Mechanisms

Registry Persistence

• Run Key: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
• Service: Windows Service with automatic startup
• Scheduled Task: Daily execution disguised as system maintenance
• WMI Subscription: Event-driven activation

File System Persistence

• Startup Folder: Shortcut in %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup
• DLL Search Order: Malicious DLL in system path
• Autorun.inf: CD-ROM autoplay for removable media
• Shell Extension: COM object registration

Detection and Analysis Tools

Static Analysis Tools

• PEiD: Packer/compiler detection
• Strings: Extracted string analysis
• IDA Pro: Disassembly and function identification
• BinDiff: Comparison with known malware samples

Dynamic Analysis Tools

• Process Monitor: System call monitoring
• Wireshark: Network traffic capture
• Regshot: Registry change detection
• API Monitor: Function call tracing

Automated Analysis

• Sandboxes: Cuckoo, Joe Security for behavioral analysis
• YARA Rules: Signature-based detection
• Machine Learning: Anomaly detection models
• Memory Forensics: Volatility for memory analysis

Attribution and Classification

Malware Family

WidePepper belongs to the “Pepper” family of advanced persistent threats, characterized by:

• Modular Architecture: Component-based design
• Sophisticated Evasion: Multi-layered anti-analysis
• Long-Term Persistence: Designed for extended operations
• Custom Protocols: Proprietary C2 communications

Threat Actor Attribution

Based on code similarities and infrastructure overlaps:

• TTP Matching: Consistent with Eastern European APT groups
• Code Signatures: Shared code patterns with known campaigns
• Infrastructure Links: C2 domains registered to similar entities
• Targeting Patterns: Focus on technology and manufacturing sectors

Mitigation Recommendations

Prevention

• Endpoint Protection: Deploy advanced antivirus solutions
• Network Monitoring: Implement intrusion detection systems
• Patch Management: Keep systems updated with latest security patches
• User Training: Educate users on phishing and social engineering

Detection

• Behavioral Analysis: Monitor for anomalous system behavior
• Signature Updates: Regular malware signature updates
• Honeypots: Deploy decoy systems for early detection
• Threat Hunting: Proactive searching for indicators of compromise

Response

• Isolation: Quarantine infected systems immediately
• Forensic Analysis: Preserve evidence for investigation
• Eradication: Remove all malware components
• Recovery: Restore systems from clean backups

Conclusion

WidePepper implant represents the current pinnacle of malware sophistication, combining advanced persistence techniques, comprehensive data collection capabilities, and robust anti-analysis measures. Its modular design and extensive functionality make it a formidable tool for cyber espionage operations. Understanding its inner workings is crucial for developing effective detection and mitigation strategies against similar advanced threats.