Cyberdudebivash

CyberDudeBivash Guidelines for RansomwareDefense

Powered by India’s emerging cybersecurity hub — CyberDudeBivash

Executive summary

Ransomware is no longer only a malware problem—it’s an identity + data + business continuity problem. Winning means designing for resilience, not perfection:

  1. Prevent common entry points.
  2. Detect abnormal behaviors early.
  3. Contain fast to stop lateral spread.
  4. Recover from immutable backups with tested playbooks.

This guide is a practical, India-first blueprint you can adopt today—whether you’re an MSME or an enterprise SOC.

Threat model (how modern ransomware wins)

Initial access: phishing, exposed RDP/VPN, vulnerable edge apps, malicious ads, supply chain.
Post-compromise: scriptable tools (PSExec/WMI), living-off-the-land, credential theft, GPO abuse.
Objectives: data theft → encryption → extortion (sometimes encryption-less extortion only).

Key MITRE ATT&CK: T1566 (Phishing), T1078 (Valid Accounts), T1021 (Remote Services), T1486 (Encrypt), T1047 (WMI), T1059 (Command & Scripting), T1110 (Brute Force), T1489 (Service Stop), T1490 (VSS deletion), T1071 (Exfil), T1484.001 (GPO).

Phase-by-phase defense (what to do)

1) Identity & Access

  • FIDO2/WebAuthn MFA for admins and finance/HR. Disable legacy/basic auth.
  • Just-in-Time privileged roles; vault and rotate break-glass accounts.
  • Conditional Access (device health, location, risk).
  • Service principal hygiene in cloud (expire secrets; least privilege).

2) Email & Web

  • DMARC (p=reject), SPF, DKIM, MTA-STS, TLS-RPT.
  • URL detonation / sandbox; block macros from the Internet; banner warn external senders.
  • DNS layer security (block newly registered domains, malware C2s).

3) Endpoints (Windows/Linux/macOS)

  • EDR everywhere (tamper protection on).
  • Windows hardening:
    • ASR rules on (block credential theft, Office child-processes, script obfuscation).
    • Controlled Folder Access for business data paths.
    • LSA protection, Credential Guard, LSASS as PPL.
    • AppLocker/WDAC allow-listing for high-risk roles.
    • Disable SMBv1; restrict RDP (NLA + VPN/jump host only).
  • Linux:
    • Mount shares with noexec,nodev,nosuid; auditd for chmod/chattr on backups;
    • restrict SSH (keys + MFA), fail2ban; EDR/AV for Linux enabled.

4) Network & Segmentation

  • Tiered admin model; isolate domain controllers, backup servers, hypervisors.
  • Block RDP/SMB from the Internet; default-deny east-west where possible; egress allow-lists.
  • LAPS or equivalent for local admin password rotation.

5) Data Protection & Backup

  • Follow 3-2-1-1-0: 3 copies, 2 media, 1 offsite, 1 immutable/air-gapped, 0 errors after restore test.
  • Object-lock/immutability for cloud backups; separate credentials & IAM boundaries.
  • Back up SaaS (M365/Google) and config (GPOs, device policies), not just files.
  • Quarterly restore drills with measured RTO/RPO.

6) Cloud & SaaS

  • Disable legacy auth; Conditional Access; session controls (sign-in risk, device compliance).
  • Safe Links/Safe Attachments (or vendor equivalent); OneDrive/SharePoint versioning & retention.
  • Protect service accounts; alert on mass download/sharing.

7) OT/ICS (if applicable)

  • Strict segmentation (conduits/zones), vendor access via jump hosts + session recording.
  • Controller backups and gold images; allow-listing on HMI/engineering workstations.

Early detection & hunting (practical)

High-signal events to alert on (Windows):

  • Shadow copy deletion: vssadmin delete shadows, wmic shadowcopy delete, diskshadow /s.
  • Backup tamper: wbadmin delete catalog, stopping backup/AV/EDR services.
  • System sabotage: bcdedit safe-mode or recovery config changes; Event ID 1102 (audit log cleared).
  • Mass file changes with unusual extensions; rapid spikes in failed file opens on shares.
  • LOLBins for staging/exfil: rclone, 7z/WinRAR with passwords, bitsadmin, certutil.

Elastic KQL (examples):

  • Process creates shadows deletion: arduinoCopyEditevent.category:process and event.action:"start" and process.command_line:( "vssadmin*delete*shadows*" or "wmic*shadowcopy*delete*" or "diskshadow*" )
  • Suspicious archiving to network share: arduinoCopyEditprocess.name:("7z.exe" or "rar.exe" or "winrar.exe") and process.command_line:("* -p*") and file.path:"\\\\*"

Microsoft Sentinel (KQL):

bashCopyEditDeviceProcessEvents
| where ProcessCommandLine has_any ("vssadmin delete", "wmic shadowcopy delete", "diskshadow")

Splunk SPL:

arduinoCopyEditindex=winsec (process="*vssadmin*" AND CommandLine="*delete*shadows*")
OR (process="*wmic*" AND CommandLine="*shadowcopy*delete*")

Rapid response playbook (when alarms fire)

0–15 min – Confirm & contain

  • Open a case; snapshot volatile data; isolate endpoints (EDR network containment).
  • Disable suspected accounts; revoke tokens/sessions; block C2 domains/IPs.
  • Stop propagation: temporarily block RDP/SMB between segments if needed.

15–60 min – Scope & kill

  • Hunt for GPO changes, new scheduled tasks, Run keys, WMI subscriptions.
  • Remove web shells / persistence; rotate creds (admins first), reset service principals.
  • If encryption started: keep encrypted hosts isolated; do not wipe yet—collect artifacts.

1–24 h – Eradicate & recover

  • Patch/close the entry vector (phish user, VPN, edge CVE).
  • Restore only from clean, immutable backups; re-introduce in rings; monitor for re-infection.
  • Report per Indian regulations: CERT-In (time-bound notification) and DPDP obligations; coordinate legal/PR.

After – Lessons & hardening

  • Root-cause report; new detections; tabletop the same scenario next week.

Hardening snippets (copy-paste starters)

Windows PowerShell – Attack Surface Reduction (common high-value rules):

powershellCopyEdit# Enable ASR rules (sample set)
$rules = @(
"56a863a9-875e-4185-98a7-b882c64b5ce5", # Block credential stealing from LSASS
"d4f940ab-401b-4efc-aadc-ad5f3c50688a", # Block Office child processes
"3b576869-a4ec-4529-8536-b80a7769e899", # Block PS exec on Win32 API
"5beb7efe-fd9a-4556-801d-275e5ffc04cc"  # Block executable content from email
)
foreach ($r in $rules) { Add-MpPreference -AttackSurfaceReductionRules_Ids $r -AttackSurfaceReductionRules_Actions Enabled }
# Controlled Folder Access
Set-MpPreference -EnableControlledFolderAccess Enabled
Add-MpPreference -ControlledFolderAccessProtectedFolders "C:\Finance","C:\Projects","\\Fileserver\Shares\Critical"

Block macros from the Internet (GPO):
User Config → Admin Templates → Microsoft Office → Block macros from running in Office files from the Internet = Enabled

Linux – protect backup indexes from tamper:

bashCopyEdit# Make backup manifest immutable (root can remove attribute after maintenance)
chattr +i /backups/manifests/index.json
# Audit rule: alert on chmod/chattr in backup paths
echo "-w /backups -p wa -k backup_tamper" >> /etc/audit/rules.d/backup.rules && augenrules --load

Samba share – reduce blast radius:

iniCopyEdit[critical]
   path = /srv/critical
   read only = no
   valid users = @finance
   write list = @finance
   veto files = /*.exe/*.js/*.bat/*.scr/
   create mask = 0640
   directory mask = 0750

Governance for India (pragmatic notes)

  • CERT-In: prepare contact list and reporting template; keep logs for 180 days by default.
  • DPDP Act: limit data collection; document lawful purpose; have breach notification playbooks.
  • Maintain vendor SLAs for IR support and forensics (time-to-engage ≤2h).

MSME “starter stack” (cost-conscious)

  • EDR (business-grade) + DNS filter + email security + backup with immutability (object lock / WORM).
  • Cloud SSO with MFA; disable legacy auth; device compliance before access.
  • Monthly restore test, quarterly tabletop exercise.
  • Run autopatching with rings (pilot → IT → all).

Metrics that matter

  • MTTD/MTTR for ransomware behaviors (VSS delete, mass encryption).
  • Patch latency for internet-facing CVEs.
  • % endpoints with ASR enabled & EDR healthy.
  • Backup success rate and restore success time.
  • Phishing click-through and report rate.

0–7 / 30 / 60 / 90-day roadmap

0–7 days: Enforce MFA, block macros-from-Internet, disable legacy auth, close exposed RDP, EDR everywhere, snapshot/validate backups, add VSS-deletion alerts.
30 days: Segment critical servers; LAPS; ringed patching; centralize logs; tune detection rules.
60 days: AppLocker/WDAC for finance/ops; immutable backup & offsite copy; SaaS backup; privileged access workstation for admins.
90 days: IR tabletop with executives; purple-team tests of encryption & exfil; automate restore runbooks.

Final word

Ransomware defense is a race against time. If you can detect early, contain within minutes, and restore with confidence, you win—no matter how the payload looks.

Need this as a one-page checklist for your team? It’s included below.

One-page Checklist (print & stick on the wall)

  • MFA (FIDO2) for admins & finance/HR
  • Legacy/basic auth off
  • EDR on 100% endpoints (tamper protection on)
  • ASR rules + Controlled Folder Access
  • RDP/SMB not exposed to Internet; VPN/jump hosts only
  • Segmented DC/backup/hypervisor networks
  • 3-2-1-1-0 backups; immutability + monthly restore test
  • Alerts: VSS delete, backup tamper, log clear, mass encryption, archiver to shares
  • Cloud: Safe Links/Attachments, versioning & retention, OAuth app review
  • Incident kit: isolation steps, contacts, CERT-In template, PR/legal counsel
  • Quarterly tabletop; update runbooks after every exercise/incident

Leave a comment

Design a site like this with WordPress.com
Get started