VECT 2.0 Ransomware Analysis: Broken Encryption Nonces and Data Wiper Behavior

Introduction

The emergence of VECT 2.0 represents a troubling shift in the ransomware landscape, not due to sophistication in its evasion techniques, but due to a catastrophic implementation failure. Recent analysis confirms that VECT 2.0 contains a critical flaw in its encryption routine: it mishandles encryption nonces during the processing of large files.

For defenders, this changes the incident response (IR) calculus significantly. This is not just a data hostage situation; it is a data destruction event. When the encryption nonces are reused or mishandled in stream ciphers (a likely implementation given the description), the mathematical integrity required for decryption collapses. In the specific case of VECT 2.0, this bug causes the malware to corrupt files beyond recovery rather than encrypting them for ransom. For organizations impacted by this variant, data recovery is impossible even if the decryption key is obtained. Immediate isolation and preservation of volatile data are paramount to understand the scope of the loss.

Technical Analysis

Affected Products/Platforms: Windows-based environments. VECT 2.0 targets standard file systems accessible from the infected user context.
Vulnerability/Mechanism: The flaw lies in the malware's implementation of cryptographic nonces (numbers used only once). In secure encryption schemes like AES-CTR or ChaCha20, a nonce must never be reused with the same key. VECT 2.0 appears to reuse nonces or generate them deterministically for large file chunks.
Impact: When a nonce is reused in a stream cipher, it allows an attacker to recover the keystream. However, in this specific "cyber incident," the malfunction results in the ransomware writing garbage data to the disk. The files are effectively wiped.
Attack Chain:
1. Initial Access: Likely via phishing or compromised credentials (standard ransomware entry vectors).
2. Execution: The ransomware binary runs, enumerating drive letters.
3. Encryption: It attempts to encrypt files. For small files, this may succeed. For large files, the nonce error triggers, corrupting the file structure.
4. Data Wiping: The file is overwritten with unusable data.
Exploitation Status: Confirmed active exploitation. The buggy code is live in the wild, posing a severe risk of data loss to victims.

Detection & Response

Detecting VECT 2.0 requires focusing on the behaviors of file encryption and the specific anomalies associated with data corruption. While the malware attempts to operate as ransomware, defenders should treat it as a wiper.

Sigma Rules

The following Sigma rules detect mass file encryption activity and the deletion of Volume Shadow Copies, a common precursor to data wiper and ransomware events.

YAML

---
title: Potential Mass File Encryption Activity
id: 3a3b3c3d-3e3f-3g3h-3i3j-3k3l3m3n3o3p
status: experimental
description: Detects a process creating or modifying a high number of files in a short period, indicative of ransomware or wiper activity like VECT 2.0.
references:
 - https://attack.mitre.org/techniques/T1486/
author: Security Arsenal
date: 2025/04/10
tags:
  - attack.impact
  - attack.t1486
logsource:
  category: file_change
  product: windows
detection:
  selection:
    EventID: 4663
    ObjectType: 'File'
    AccessMask: '0x1' # Write access
  timeframe: 5m
  condition: selection | count() > 50
falsepositives:
  - Legitimate bulk file operations (e.g., software updates, backups)
level: high
---
title: Deletion of Volume Shadow Copies via VssAdmin
id: 1a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects the execution of vssadmin to delete shadow copies, often performed by ransomware and wipers to prevent recovery.
references:
 - https://attack.mitre.org/techniques/T1490/
author: Security Arsenal
date: 2025/04/10
tags:
  - attack.impact
  - attack.t1490
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|endswith: '\vssadmin.exe'
    CommandLine|contains: 'delete shadows'
falsepositives:
  - Administrative system maintenance
level: high

KQL (Microsoft Sentinel)

This query hunts for processes modifying files with common ransomware or data-wiping patterns, specifically looking for the high-frequency file access associated with VECT 2.0.

KQL — Microsoft Sentinel / Defender

DeviceProcessEvents
| where Timestamp > ago(1d)
| where ProcessVersionInfoOriginalFileName in ('vssadmin.exe', 'powershell.exe', 'cmd.exe') 
   or FileName =~ 'powershell.exe'
| extend CommandLine = coalesce(ProcessCommandLine, '')
| where CommandLine contains "delete" and CommandLine contains "shadow" 
   or CommandLine contains "encryption" 
   or CommandLine contains "-encrypt"
| project Timestamp, DeviceName, InitiatingProcessAccountName, FileName, CommandLine, FolderPath

Velociraptor VQL

This Velociraptor artifact hunts for the presence of suspicious executables in user directories or common download locations that may be associated with the VECT 2.0 deployment, and checks for ransom note files.

VQL — Velociraptor

-- Hunt for VECT 2.0 executables and ransom notes
SELECT FullPath, Size, Mtime, Mode
FROM glob(globs="C:/Users/*/AppData/Local/Temp/*.exe")
WHERE Size < 5000000 AND Size > 100000 
   -- Filter for suspicious size ranges typical of droppers
UNION ALL
SELECT FullPath, Size, Mtime, Mode
FROM glob(globs="C:/Users/*/*VECT*")
-- Hunt for ransom notes containing VECT naming convention
UNION ALL
SELECT FullPath, Size, Mtime, Mode
FROM glob(globs="C:/Users/*/Desktop/*RECOVER*.txt")

Remediation Script (PowerShell)

Use this script to isolate an affected host immediately upon suspicion of VECT 2.0 activity. It kills suspicious processes and disables network interfaces to halt data exfiltration or lateral movement.

PowerShell

# VECT 2.0 Isolation and Containment Script
# Requires Administrator Privileges

Write-Host "[+] Starting VECT 2.0 Containment Procedures..."

# 1. Kill suspicious processes (common ransomware/wrapper names)
$suspiciousProcesses = @("vect", "decryptor", "payload", "temp", "loader")
Get-Process | Where-Object { $suspiciousProcesses -match $_.ProcessName } | Stop-Process -Force -ErrorAction SilentlyContinue

# 2. Disable Network Adapters to contain the spread
Disable-NetAdapter -Name "*" -Confirm:$false -ErrorAction SilentlyContinue
Write-Host "[+] Network adapters disabled."

# 3. Create a forensic snapshot of running processes (for IR analysis)
$outPath = "C:\IR_Snapshot"
if (-not (Test-Path $outPath)) { New-Item -ItemType Directory -Path $outPath }
Get-Process | Select-Object ProcessName, Id, Path, StartTime | Export-Csv -Path "$outPath\process_list.csv" -NoTypeInformation

Write-Host "[+] System isolated and volatile data collected. Do not reboot. Contact IR team."

Remediation

Given the destructive nature of VECT 2.0, standard decryption is impossible for affected large files due to the nonce reuse bug.

Immediate Isolation: Disconnect infected hosts from the network immediately to prevent further data loss and lateral movement.
Forensic Imaging: Because the files are destroyed, preserving the state of the disk (unallocated space, $LogFile, $MFT) is critical to confirm the wiper mechanism and identify the initial access vector.
Data Restoration: Recovery must rely solely on offline backups. Ensure you restore from a backup created before the initial infection timestamp.
Patch and Hunt: While there is no "patch" for this specific ransomware bug, update endpoint detection rules (EDR) to include the Sigma signatures provided above. Hunt for the initial access vector—often compromised credentials or unpatched RDP services.
Vendor Advisory: Monitor security vendor feeds for specific IOCs (Indicators of Compromise) such as file hashes or C2 domains associated with VECT 2.0 and block them at the perimeter.

Related Resources

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