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The CISO’s OAuth IR Playbook: A Step-by-Step Guide to Finding and Revoking Malicious M365 & Salesforce Apps Before They Cost You Millions

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The CISO’s OAuth IR Playbook: Step-by-Step Guide to Finding & Revoking Malicious M365 & Salesforce Apps

By CyberDudeBivash · Daily Threat Intel & AppSec · Apps & Services · Threat Analysis · News · Crypto Security

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TL;DR 

Edureka
Upskill SOC/Cloud IR teams—role-ready courses.Alibaba Cloud
Global infra & backups for IR/business continuity.Kaspersky
Endpoint & mail security to cut OAuth phish risk.AliExpress
Budget IR gear: YubiKeys, cables, lab parts.

Disclosure: We may earn a commission from partner links. Recommended by CyberDudeBivash for professional teams.Table of Contents

  1. Why OAuth Abuse Evades MFA & Traditional Detections
  2. 90-Minute QuickCheck (Microsoft 365)
  3. 90-Minute QuickCheck (Salesforce)
  4. Validate: Scope, Risk, Blast Radius
  5. Revoke: Tokens, Consents, Secrets
  6. Remediate: Policies, CA, Governance
  7. Monitor: Detections, SIEM, Hunting
  8. Playbooks & Automation Snippets
  9. Comms, Legal, and Evidence Handling
  10. 7-Day Hardening & 30-Day Controls Roadmap
  11. FAQ

OAuth is the cloud era’s favorite trust shortcut—and the attacker’s dream. A single “Consent” click lets a third-party app read mailboxes, files, calendars, and CRM data without a password prompt, often persisting through resets. This playbook distills hundreds of OAuth incidents into a repeatable IR method for CISOs and enterprise security leaders running Microsoft 365 (Entra ID/Azure AD) and Salesforce.

You’ll learn to Find ungoverned apps, Validate true risk, Revoke the access safely, and Remediate controls—fast. Every step includes operational guidance plus optional automation snippets your SOC can use today.

1) Why OAuth Abuse Evades MFA & Traditional Detections

  • Token-centric access: OAuth uses refresh/access tokens. Once granted, attacker-controlled apps pull data without user logins—MFA never triggers.
  • Scope overreach: Excessive scopes (Mail.Read, Files.Read.All, offline_access) enable quiet exfiltration.
  • Human-trusted UX: Users click “consent” in the context of productivity, helpdesk, or AI helpers. Security awareness rarely covers OAuth.
  • Shadow IT in plain sight: Legit tooling + rogue apps look alike across tenants; logs are noisy, and defaults often allow user consent.

Pro Tip (Procurement x Security): Add an OAuth App Risk Review checkpoint for all SaaS intake. CISOs: make it a board-visible KPI.

2) 90-Minute QuickCheck (Microsoft 365)

  1. Enumerate enterprise/apps in Entra ID:
    • Portal: Entra ID → Enterprise applications; filter: “All applications”, add columns: Publisher verification, Permissions, User consent.
    • Look for: Unverified publishers, multi-tenant apps, rare names, recently added, high-risk scopes, consented by VIPs.
  2. Pull via Graph (sample idea):GET https://graph.microsoft.com/v1.0/servicePrincipals?$select=id,appId,displayName,publisherName,verifiedPublisherDisplayName,signInAudience &$filter=servicePrincipalType eq ‘Application’ (Use app registrations + delegated permissions setup; store safely; rotate secrets.)
  3. Spot dangerous scopes in API permissions:
    • Mail.Read, Mail.ReadWrite, Mail.Send, Files.Read.All, Files.ReadWrite.All, Sites.Read.All, offline_access, User.Read.All.
  4. Check audit (Unified Audit Log / Entra sign-ins): New consent events, service principal sign-ins from odd IPs, exfil patterns (large Graph reads).
  5. Containment option: Conditional Access policy to block risky app or require admin consent workflow instantly (see “Remediate”).

Harden M365 endpoints with Kaspersky →

3) 90-Minute QuickCheck (Salesforce)

  1. Connected Apps: Setup → App Manager → Connected Apps. Export app list, note Perm Sets, Profiles, Policies, IP ranges.
  2. OAuth scopes: Flag apps with Perform requests on your behalf at any time, Access and manage your data (api), Full access (full).
  3. Session policies: Require high-assurance SSO for privileged apps, enforce IP restrictions and refresh token policies.
  4. Event Monitoring: Look for unusual API spikes, bulk data extracts, login anomalies from new integrations.

Quick containment: freeze the suspicious Connected App, revoke session tokens, rotate integration user creds, and notify owners.

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4) Validate: Scope, Risk, Blast Radius

Confirm the app is malicious or over-permissive before revocation to avoid breaking business-critical workflows. Validate quickly:

  • Scope intent vs. function: Does a “calendar assistant” need Files.ReadWrite.All? No → escalate.
  • Publisher verification: Unverified or lookalike publishers warrant immediate quarantine.
  • Data touched: Which mailboxes, sites, OneDrive, SharePoint, Teams, or Salesforce objects were read or written?
  • Who consented: VIPs, admins, service accounts = higher severity.

Evidence tip: Preserve Graph API call logs, app registration metadata, consent records, and Salesforce event logs with hash + timestamp.

5) Revoke: Tokens, Consents, Secrets

  1. Microsoft 365:
    • Remove user consent (Enterprise applications → Permissions) and/or disable/delete the service principal.
    • Invalidate refresh tokens: Revoke-SignIn Sessions for impacted users & app.
    • Rotate app secrets/certs; purge unused App Registrations.
  2. Salesforce:
    • Block App (Connected App policies), revoke all sessions.
    • Reset OAuth policies (IP restrictions, high-assurance login, session timeout).
    • Rotate integration user passwords and connected certificates.
  3. Comms: Notify app owners and business stakeholders; provide business-impact ETA and workarounds.

Recommended: Issue corporate cards (Asus/HSBC partners) for vetted SaaS only →

6) Remediate: Policies, CA, Governance

6.1 Microsoft 365 (Entra ID / Azure AD)

  • Disable user consent to apps; enable admin consent workflow.
  • Conditional Access: block unverified publishers; require compliant devices for app-backed sign-ins.
  • App governance: review Permissions monthly; auto-expire consents; enforce verified publishers only.
  • Defender for Cloud Apps (MCAS) policies: OAuth app discovery, risky app alerts, session controls.

6.2 Salesforce

  • High Assurance Session for privileged Connected Apps; restrict to SSO.
  • Refresh Token Policy: “Expire immediately” on revocation; minimize “offline-like” access.
  • Profiles/Perm Sets: Principle of least privilege; segregate integration users.

6.3 Organization-wide

  • Vendor risk: Mandate publisher verification or enterprise SSO for third-party apps.
  • IAM playbook binding: Merge this OAuth IR into your corporate Incident Response Plan and BCP/DR docs.

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7) Monitor: Detections, SIEM, Hunting

Log sources to onboard: Entra ID audit & sign-ins, Unified Audit Log, Graph activity (if available), MCAS alerts, Salesforce Event Monitoring, secure email gateway logs.

Detection ideas (names/gist)

  • New consent spike with high-risk scopes in 24h window.
  • Service principal sign-ins from rare geos or TOR/VPN ASNs.
  • Graph heavy reads of mail/files right after consent.
  • Salesforce API export volumes outside normal business hours.

Hunt starter (concept): Join service principal sign-ins with mailbox/file access to identify first-touch → data pull patterns for the same app ID.

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8) Playbooks & Automation Snippets

8.1 “Find-Validate-Revoke-Remediate” Checklist (Printable)

  1. Find: Enumerate apps (M365 + SF). Tag unverified publishers & risky scopes.
  2. Validate: Confirm business purpose; map data touched; score blast radius.
  3. Revoke: Remove consents; revoke sessions; rotate secrets; freeze app.
  4. Remediate: Enforce admin consent workflow; CA; governance; SIEM rules.

8.2 PowerShell (conceptual, safe)

# PSEUDO/CONCEPT — Illustrative only
# Connect-MgGraph -Scopes "Application.Read.All,Directory.Read.All"
# List risky service principals by unverified publisher or suspicious display name pattern.
# Use official Graph modules, store creds in secure vaults, and apply least privilege.

8.3 SOAR Tasks

  • Create ticket with app metadata + scopes + who consented + data touched.
  • Auto-send owner validation form; escalate if no response in 2h.
  • On “malicious/unknown,” call revocation steps; notify comms/legal.

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9) Comms, Legal, Evidence Handling

  • Evidence: Preserve logs, consent records, app metadata, and data-access trails with chain-of-custody notes.
  • Notices: Regulatory and customer communications (if PII/PHI accessed). Coordinate with Data Protection Officer.
  • Internal comms: One-pager with what happened, actions taken, business impact, and next steps. Keep to facts; avoid speculation.

Include third-party app vendors in post-incident reviews; require secure SDLC attestations and app verification commitments.

10) 7-Day Hardening & 30-Day Controls Roadmap

Day 0–1

  • Disable user consent; enable admin consent workflow (M365). Freeze suspicious Salesforce Connected Apps.
  • Block unverified publishers via Conditional Access. Tighten refresh token lifetimes on critical apps.

Day 2–3

  • Catalog apps by scope & owner; remove stale apps; rotate secrets/certs.
  • Deploy MCAS OAuth governance; add SIEM detections for consent anomalies.

Day 4–7

  • Tabletop exercise: “Malicious Consent to Data Exfil App.” Validate comms, legal, and SOAR timings.
  • Ship policy updates to procurement & DevRel: mandatory app verification or SSO, periodic consent reviews.

30-Day Program

  • Quarterly consent attestation by app owners, continuous discovery, vendor risk scoring, and red-team simulation.

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Need Help Right Now? Engage CyberDudeBivash IR & App Governance Team

  • Emergency OAuth Breach Response (M365 / Salesforce)
  • Consent Governance & Admin-Consent Rollout
  • MCAS/CASB Policies, SIEM Detections & SOAR Playbooks
  • Board-level Reporting & Tabletop Workshops

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Next Reads from CyberDudeBivash

FAQ

Is disabling user consent too strict?

No. Pair it with an admin consent workflow and a fast review SLA. You’ll cut 90% of risky consents without hurting productivity.

How do we avoid breaking legitimate integrations?

Maintain a golden allowlist of verified apps. Communicate changes in advance; provide alternates via SSO & SCIM.

Which scopes are the biggest red flags?

Files.Read.All, Files.ReadWrite.All, Mail.Read, Mail.ReadWrite, Mail.Send, Sites.Read.All, and offline_access.

What should I present to the board?

A one-pager: incident cause, data at risk, containment time, policy changes (admin consent, CA), and a 30-day roadmap.

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

Author: CyberDudeBivash · Powered by CyberDudeBivash · © All Rights Reserved.

 #CyberDudeBivash #OAuth #Microsoft365 #Salesforce #IncidentResponse #CISO #AppSec #CloudSecurity #ThreatIntel

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