For a CTI analyst, running malware in a sandbox is useful, but extracting the Configuration is gold. The configuration contains the "hardcoded secrets" of the malware: C2 IP addresses, domain generation algorithms, and encryption keys.
Extracting this data allows you to block future C2 infrastructure before it is even activated.
The Static Analysis Workflow
1. Identifying Strings
The strings command is the first step. It extracts readable text from the binary.
- Look for: IP addresses, URLs, PDB paths (debug info), and error messages.
- Obfuscation: Most modern malware encrypts these strings to hide them from basic analysis.
2. De-obfuscation with CyberChef
CyberChef is the "Swiss Army Knife" of CTI analysts.
- Scenario: You find a suspicious PowerShell script with a large blob of Base64 text.
- Action: Copy the blob into CyberChef -> Apply
From Base64-> Look for recognizable code. - Advanced: Malware often uses XOR encryption. Use the
XOR Brute Forcerecipe in CyberChef to find the key and reveal the hidden C2 URL.
3. Finding the Config Block
In compiled malware (EXE/DLL), the configuration is often stored in the .data or .rdata section.
- Tool: Use PEStudio or CPA (Capabl) to identify suspicious capabilities and encrypted blocks.
- Goal: Once you extract the config, you can write a YARA Rule to detect not just this sample, but any sample sharing that specific configuration structure.
Why Extraction Matters?
Sandboxes have a time limit (e.g., 5 minutes). If the malware is programmed to sleep for 20 minutes (evasion), the sandbox will report it as "clean." Static analysis bypasses this sleep timer because you are looking at the code itself, not its behavior.