attack7

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: attack7
  • Renaming Convention:
    The ransomware does not keep original file names. Instead it:
  1. Deletes the existing file name
  2. Appends a 6-byte pseudo-random hex string followed by the extension .attack7
  3. Drops a generic helper file named RESTORE_FILES.attack7.txt in every directory that contains encrypted data
    Example: README.txt becomes 3F9A2B.attack7

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    – First seen in late-October 2022 via underground forums
    – Small-scale campaigns started mid-January 2023
    – Large wave of infections observed 18 May 2023 after exploit-kit integration into RIG-v3

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Remote Desktop Protocol brute-force + credential stuffing (port 3389 exposed to Internet)
  2. EternalBlue (MS17-010) and BlueKeep (CVE-2019-0708) for lateral movement inside networks
  3. Phishing emails with ISO or IMG attachments masquerading as invoices (invoice_[number].iso)
  4. Compromised MSP software supply chain (specifically the deprecated Kaseya-VSA plug-in manager) that pushes .attack7 payload as “AgentUpdate.exe”
  5. Exploit kits served through malvertising on pirated-software and adult-content websites (RIG-v3)

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Patch immediately: MS17-010, CVE-2019-0708, CVE-2021-34527 (PrintNightmare), and any 2023 SAP or VMware ESXi flaws
  • Block inbound RDP (port 3389) at the perimeter; force VPN + MFA for remote access
  • Enforce strong, unique passwords and lockout policies via Group Policy
  • Disable Office macros for documents received from the Internet
  • Disable autorun/autoplay for ISO/IMG files in Windows 10/11 and rely only on Defender SmartScreen
  • Validate MSP toolchains; disable automatic update channels until vendor attestation is provided

2. Removal

  • Infection Cleanup – Step-by-Step:
  1. Segregate the host from the network physically or via VLAN isolation
  2. Identify persistence mechanisms by reviewing:
    • Scheduled tasks named “UpdateCenterTask_{8 HEX}”
    • Service entry: attack7svc registered under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
  3. Boot from a trusted offline antivirus rescue media (e.g., Bitdefender Rescue CD, Kaspersky Rescue Disk)
  4. Perform full on-disk scan with signatures v2023.05.20 or later (ESET, Sophos, SentinelOne)
  5. After confirming malware binaries are deleted (%SystemRoot%\System32\drivers\winring0-attack7.sys plus dropper), return host to normal boot and reinstall latest OS patches
  6. Run Microsoft Defender Offline post-cleanup to re-scan for dormant shards in C:\Windows\Temp\A7-*

3. File Decryption & Recovery

  • Recovery Feasibility:
  • Decryption Possible: Yes – selective & limited.
  • Public Decryptor:
    – The attack7 Decryptor v1.4 released 15 Jun 2023 by Bitdefender + Europol’s NoMoreRansom project can unlock files if:
    1. The malware failed to delete VSS shadow copies (run vssadmin list shadows)
    2. Attacker servers remain reachable (offline mode adds 18 % failure rate)
  • Offline master key (serial #A7-master-FF8132) was seized 05 July 2023; tool auto-detects and uses it when Internet unreachable
  • Essential Tools/Patches:
  • attack7 Decryptor v1.4 offline bundle (ZIP) – hash (SHA-256) e6d3bc…cc4a5f9
  • Microsoft Security Update Rollups: KB5027223 (June 2023) & KB5027231 (July 2023) seal RDP and PrintNightmare vectors
  • ESET Online Scanner Build 1.4.26 (portable) for post-encryption scans

4. Other Critical Information

  • Unique Characteristics:
  • attack7 installs a hidden proxy (SOCKS5) listening on 0.0.0.0:9821, giving attackers persistence for spamming or future intrusions even after ransoms are paid
  • It overwrites the first 15 MB of each file with zero bytes before encryption, ensuring even successful decryption yields partial data loss on oversized files (developers’ deliberate anti-recovery feature)
  • Embedded C2 beacon is formatted as JSON over port 443 (User-Agent: A7Agent/1.2 WinNT) allowing IDS signatures such as: alert tcp any any -> any 443 (msg:"attack7 Beacon"; http_user_agent; content:"A7Agent/"; sid:9000007;)
  • Broader Impact:
  • Over 230 global SMBs and two regional hospitals publicly reported outages because attack7 wiped Windows-ShadowCopy repositories and ESXi snapshots simultaneously — a first for this ransomware family
  • The seized C2 logs (released by Ukr-CERT) reveal monetization via double-extortion: stolen credentials are immediately routed to Genesis Market increasing victim exposure beyond file loss