Lumma Infostealer is Hijacking Your M365 SessionsA 5-Step Playbook to Hunt for Stolen RDP/VPN Credentials & Cookie-Based MFA Bypasses NOW

By CyberDudeBivash · M365 IR, Identity & Endpoint Defense · Apps & Services · Playbooks · ThreatWire · Crypto Security

CyberDudeBivash®

TL;DR

Problem: Infostealers loot browser cookies, OAuth tokens, and saved creds, enabling session replay into M365, RDP, and VPN—often bypassing MFA.
Plan: 90-minute triage → host & identity hunts → token/app revocation → password & key rotation → 7-day hardening.
Outcome: Reduced blast radius, verified eviction, and measurable MTTR for session hijacks and credential abuse.

Edureka
SOC/M365 IR & KQL training—team-ready.Alibaba Cloud
Immutable backups & vault for IR evidence.Kaspersky
Reduce commodity noise to surface real hijacks.AliExpress
IR lab gear: hardware keys, SSDs, taps, analyzers.

Disclosure: We may earn commissions from partner links. Handpicked by CyberDudeBivash.Table of Contents

Threat Model: Cookie Theft → Session Replay

Initial access: drive-by downloads, fake updates, malvertising, or cracked-ware dropper → infostealer.
Loot: browser cookies, refresh tokens, saved passwords, RDP/VPN creds, crypto extensions, autofill.
Abuse: logins from new ASNs/devices; mailbox/file access surges; OAuth app creation/consent; VPN/RDP from odd geos; staged exfil via SaaS APIs.

This article is defense-only. No exploit or malware operation instructions—just how to detect, contain, and harden.

90-Minute QuickCheck: Blast Radius

Who is targeted? Pull last 7–14 days of Defender AV/EDR hits tagged “credential/infostealer” on endpoints; list primary users.
Identity drift: In Entra ID/Sentinel, compare country/ASN diversity per user in 48h. Flag >1 geo or ASN for non-travelers.
High-risk events: “Consent to application” events; “MailItemsAccessed” surges; new inbox rules; external sharing bursts.
Remote access: VPN/RDP logins from rare IPs; multiple users from same new ASN; failed → success chains.
Fast containment: Force sign-out and token revoke for confirmed users while evidence is exported and preserved.

Hunt Playbooks (Host • Identity • Network)

1) Host (Windows/macOS/Linux) — EDR & Browser Hygiene

Endpoint indicators: new binaries in %ProgramData%, %AppData%, ~/Library/, or ~/.config/; browser profile tampering; suspicious ZIP/RAR/7z → browser crashes → new processes.
Queries (concept): find processes spawning browsers or reading browser DBs; file writes to browser profile folders; network to known stealer infra (using your TI allowlist/blocklist).

2) Identity (Entra ID/M365) — KQL Hunt Pack

// A) Risky OAuth Consents (24–48h)
AuditLogs
| where TimeGenerated > ago(48h) and OperationName has "Consent to application"
| extend App=tostring(TargetResources[0].displayName),
         Scopes=tostring(TargetResources[0].modifiedProperties[?].newValue),
         Actor=tostring(InitiatedBy.user.userPrincipalName)
| where Scopes has_any ("Mail.Read","Files.Read.All","Files.ReadWrite.All","offline_access","Sites.Read.All","User.Read.All")
| summarize Consents=count(), Actors=make_set(Actor) by App, Scopes

// B) Geo/ASN Drift (User Sessions)
SigninLogs
| where TimeGenerated > ago(48h) and ResultType == 0
| summarize Geos=dcount(LocationDetails.countryOrRegion), ASNs=dcount(NetworkLocationDetails.asn)
  by UPN=UserPrincipalName
| where Geos > 1 or ASNs > 1

// C) Mailbox Access Surge After Consent
let W=AuditLogs
| where TimeGenerated > ago(72h) and OperationName has "Consent to application"
| project Consenter=tostring(InitiatedBy.user.userPrincipalName), ConsentTime=TimeGenerated;
OfficeActivity
| where TimeGenerated > ago(72h) and Operation =~ "MailItemsAccessed"
| join kind=inner W on $left.UserId == $right.Consenter
| summarize Accesses=count(), First=min(TimeGenerated), Last=max(TimeGenerated) by UserId
| where Accesses > 200

// D) New Inbox Rules / Forwarding (7d)
OfficeActivity
| where TimeGenerated > ago(7d)
| where Operation has_any ("New-InboxRule","Set-InboxRule","Set-Mailbox","UpdateInboxRules")
| summarize Rules=count(), sample=any(Parameters) by UserId
| where Rules > 0

3) Network (VPN/RDP/Proxy/Firewall)

VPN: new devices or client versions from rare ASNs; multiple compromised users emerging from the same exit IP.
RDP: successful logons after bursts of failures; lateral moves from jump hosts outside normal windows.
Proxy: sudden hits to look-alike SaaS/SSO domains; downloads of unsigned “updaters.”

PowerShell/Graph Concepts (Read-Only Exports)

Run from a hardened jump box; use read-only scopes to export evidence. No tenant changes here.

# Connect-MgGraph -Scopes "AuditLog.Read.All,Directory.Read.All,Reports.Read.All,IdentityRiskEvent.Read.All,SecurityEvents.Read.All"
# List recent risk sign-ins (concept)
# GET https://graph.microsoft.com/v1.0/identityProtection/riskySignIns?$top=200

# Enumerate Enterprise Apps & service principals (concept)
# GET https://graph.microsoft.com/v1.0/servicePrincipals?$select=id,appId,displayName,verifiedPublisher,signInAudience&$top=999

# Export mailbox rule changes (concept via Search-UnifiedAuditLog or Graph reports)

Containment: Revoke, Rotate, Re-enroll

Sessions: Force sign-out & revoke refresh tokens for affected users; require password reset; re-register strong auth per policy.
Apps: Remove user consents; block sign-ins; delete obviously malicious Enterprise Apps after evidence export.
Browsers: Clear cookies; sign out of all profiles; update browsers; remove unapproved extensions; rotate saved passwords.
RDP/VPN: Rotate credentials and revoke device certs/keys; require re-enrollment on compliant devices only.
Evidence: Preserve exports/logs with hashes in a write-once vault; document timeline and revocation receipts.

Secure remote IR with TurboVPN (teams) →

7-Day Hardening Plan

Day 0–1 — Stop the Bleeding

Disable end-user consent; enable admin-consent workflow with SLA and reviewers.
Enforce phishing-resistant MFA (hardware security keys) for admins, finance, HR, and app owners.
Conditional Access: block unverified publishers; require compliant/hybrid-joined devices for risky scopes.

Day 2–4 — Prove Control

Audit and rotate OAuth app secrets; delete unused registrations; assign owners to every app.
Deploy SIEM alerts: consent events; rare ASN sign-ins; MailItemsAccessed surges; new inbox rules; VPN/RDP anomalies.
Harden browsers via policy: disable password storage for privileged roles; allowlist extensions; force auto-update.

Day 5–7 — Make It Boring

Monthly permission attestations; auto-expire stale consents; quarterly tabletop (“Infostealer → Token Replay”).
EDR controls: alert on access to browser credential stores; block untrusted updaters; quarantine known stealer families.

The Hindu (Pro) — policy & breach reporting intel YES Education — SOC/M365 IR upskilling VPN hidemy.name — secure IR travel Tata Neu — cards & perks for SaaS

Need Expert Help? Engage CyberDudeBivash M365 IR & App Governance

Emergency session-hijack response (Exchange/SharePoint/Teams)
Admin-consent workflow & app governance rollout
SIEM/KQL detections & SOAR revocation playbooks
Board reporting & tabletop workshops

Explore Apps & Services | cyberdudebivash.com · cyberbivash.blogspot.com · cyberdudebivash-news.blogspot.com · cryptobivash.code.blog

Next Reads from CyberDudeBivash

FAQ

Does this article include malware operation details?

No. It’s defense-only—focused on detection, containment, and hardening against session hijack and credential abuse.

Will forcing hardware MFA stop cookie replay?

It dramatically reduces risk, especially when paired with device compliance and short session lifetimes. You must also revoke tokens and clear cookies.

What’s the fastest win today?

Disable end-user consent, enable admin-consent workflow, deploy the KQL hunts, force sign-out for impacted users, and rotate VPN/RDP creds.

Do we need to wipe machines?

If the endpoint shows infostealer activity or persistence, rebuild from a known-good image after evidence capture.

CyberDudeBivash — Global Cybersecurity Brand · cyberdudebivash.com · cyberbivash.blogspot.com · cyberdudebivash-news.blogspot.com · cryptobivash.code.blog

#CyberDudeBivash #Lumma #Infostealer #M365 #OAuth #KQL #ConsentPhishing #RDP #VPN #IncidentResponse

Cyberdudebivash