How to Uncover the Hidden Wiper Flaw in VECT Ransomware

Introduction

This guide helps security researchers and incident responders identify the critical cryptographic flaw in VECT ransomware (version 2.0) that turns it into an unintentional data wiper. Instead of encrypting large files, VECT permanently destroys them due to a nonce-handling error in its ChaCha20 implementation. By following these steps, you will learn how to recognize the flaw, confirm its presence across Windows, Linux, and ESXi variants, and understand why even the attacker cannot recover lost data. The information here is based on Check Point Research findings—all facts are preserved, but the content is completely rewritten for clarity.

What You Need

• Access to VECT ransomware samples (Windows, Linux, and ESXi variants) – obtain from malware repositories or incident artifacts.
• Reverse engineering tools – IDA Pro, Ghidra, or any disassembler that supports x86, x64, and ELF/PE formats.
• Knowledge of ChaCha20 cipher – specifically the IETF variant (RFC 8439) and understanding of nonce construction.
• Hex editor – to examine raw encrypted files and identify nonce patterns.
• Test environment – isolated sandbox for dynamic analysis (optional but recommended).
• Patience and attention to detail – the flaw is subtle but devastating.

Step-by-Step Guide

Step 1: Identify the Ransomware Variant and Platform

Begin by confirming you are dealing with VECT ransomware version 2.0. Check for signs such as the file extension (often .vect or similar), the ransom note content mentioning TeamPCP partnership, or the presence of speed flags (--fast, --medium, --secure) in Linux and ESXi binaries. Note that the encryption engine is identical across Windows, Linux, and ESXi—this unified design is a key clue. If you find these indicators, proceed to examine the encryption routine.

Step 2: Locate the Encryption Function and Identify the Cipher

Reverse-engineer the binary to find the file encryption routine. Look for calls to crypto_stream_chacha20_ietf or similar libsodium functions. Public reports often misidentify the cipher as ChaCha20-Poly1305 AEAD, but you will see no Poly1305 MAC being computed or attached. Confirm that the cipher is raw ChaCha20-IETF (RFC 8439) without authentication. The absence of integrity checks means files can be corrupted silently.

Step 3: Analyze the Chunking Logic and Nonce Generation

Examine how the ransomware processes files. VECT splits files into four fixed-size chunks regardless of the actual file length. For files larger than 131,072 bytes (128 KB), each chunk except the first is assigned a nonce that is derived incorrectly. Look at the nonce generation code: typically, a 12-byte nonce is created from a per-file random value and a chunk index. However, due to a bug, three out of four chunk nonces become deterministic duplicates of the first chunk’s nonce or are otherwise flawed. This means the same keystream is used for multiple chunks.

Step 4: Confirm the Nonce Flaw on Different File Sizes

Test the encryption with file sizes below and above 128 KB. For small files (<131,072 bytes), the flaw is not triggered because only one chunk is used. For large files (e.g., a 1 MB image), encrypt the file and then examine the raw output with a hex editor. Compare the encrypted blocks: you will notice that blocks after the first 128 KB exhibit patterns that indicate the same keystream is being applied. This makes full recovery impossible—even with the decryption key, the nonce duplication prevents correct decryption. This behavior effectively turns the ransomware into a wiper for any file containing meaningful data, including VM disks and databases.

Step 5: Verify That Speed Modes Are Ignored

Look at how the code handles command-line flags like --fast, --medium, or --secure. Despite being parsed, these flags are silently ignored. The same hardcoded encryption thresholds (the four-chunk logic) are applied every time. This means that regardless of the operator’s choice, the encryption behavior remains constant. Use dynamic analysis with different flag values to confirm that the encrypted output is identical for the same input file.

Step 6: Document Additional Bugs and Design Failures

Beyond the nonce flaw, identify other weaknesses. Look for self-cancelling string obfuscation routines that produce no effect, permanently unreachable anti-analysis code that never executes, and a thread scheduler that actually degrades encryption performance instead of improving it. These amateurish mistakes confirm that despite a professional-looking facade, VECT’s implementation is deeply flawed. Compile your findings into a report highlighting that the ransomware cannot reliably encrypt or decrypt, and that victims lose data permanently.

Tips for Analysts

• Test on harmless dummy files first – create small (<128 KB) and large (>128 KB) test files to easily observe the flaw.
• Compare with legitimate ChaCha20-IETF – use a reference implementation to see what correct nonce management should produce.
• Check for other ransomware families – the same nonce duplication bug may appear elsewhere, so keep an eye out for similar chunking patterns.
• Share your findings responsibly – this flaw means victims cannot pay for decryption; warn affected organizations to focus on backups rather than recovery.
• Remember the partnership context – VECT’s tie to TeamPCP and BreachForums emphasizes that even cybercriminals can release buggy tools; vigilance pays off.