Executive summary (TL;DR)

Most successful breaches today never drop a binary. Attackers weaponize identity, misconfigurations, and built-in tools to move fast and stay invisible: SSO session theft, OAuth consent abuse, over-permissive cloud roles, remote administration utilities, and living-off-the-land binaries (LOLBins). These malware-free intrusions slip past AV and signature-centric controls, compress dwell time from days to hours, and hit impact (data theft, ransomware deployment by built-in tools, cloud resource hijack) before classic detections even wake up.

What is a malware-free intrusion?

A breach that achieves objectives without introducing foreign executables. Instead it uses:

• Stolen credentials / tokens (cookies, refresh tokens, OAuth grants, PATs, API keys).

• Built-in OS and cloud tooling (PowerShell, WMI, PsExec/WinRM, gcloud/aws/az CLIs, kubectl, SQL clients).

• SaaS features (Share links, Inbox rules, OAuth apps, Admin APIs).

• Legitimate remote software already present (AnyDesk, ScreenConnect, RMM agents).

Why it works: Security stacks tuned for “malware = bad binary” miss identity- and behavior-led attacks, especially when the actor blends into business-as-usual.

The attacker’s playbook (end-to-end)

1. Recon

   • Harvest public OSINT to map org structure and tech stack.

   • Enumerate identity fabric: IdP, MFA gaps, OAuth policies, SSO apps, CI/CD, cloud providers.

2. Initial access

   • Phishing/vishing/deepfake for credentials or session hijack (AitM kits, reverse proxies).

   • Password spraying / MFA fatigue / SIM swap for one-time bypass.

   • “Legit” OAuth app asking for broad scopes (admin consent fatigue).

3. Establish foothold

   • Convert creds into long-lived access: refresh tokens, OAuth grants, PATs, service-principal secrets.

   • Create inbox rules & persistence in IdP (app consents, new security keys, device registrations).

4. Privilege escalation

   • Analyze policies to find role misconfigurations; exploit trust between tenants/projects; abuse conditional-access gaps; pivot via service principals, workload identities, GitHub actions, or CI/CD runners.

5. Lateral movement

   • Use RMM/remote shells already deployed; WMI/WinRM/SSH; cloud assume-role; kubecontext hops; SQL linked servers.

   • Mount file shares, exfil via sanctioned SaaS (Drive, OneDrive, S3 pre-signed URLs).

6. Actions on objectives

   • Quiet exfil; business-email-compromise (BEC); cloud cryptomining; or rapid ransomware using native tools (Volume Shadow Copy deletions, BitLocker/ESXi encrypt via management APIs).

Common failure points you can fix this week

• Phishing-resistant MFA not enforced for admins and service accounts.

• Admin consent allowed for unverified OAuth apps; no review workflow.

• Over-permissive cloud IAM (“:” wildcards, standing admin roles, shared keys).

• No egress controls for privileged hosts; AI/LLM endpoints and RMM domains wide open.

• SIEM blind to identity events (OAuth grants, service-principal changes, token anomalies).

• Endpoint allow-lists missing for PsExec/WMIC/PowerShell/Certutil; ASR rules disabled.

MITRE ATT&CK® mapping (high-probability in malware-free cases)

• Initial Access: T1566 Phishing, T1195 Supply Chain (SaaS/OAuth)

• Execution: T1059 Command & Scripting Interpreter, T1106 Native API

• Persistence: T1136 Create Accounts (Cloud), T1098 Account Manipulation, OAuth grants

• Privilege Escalation: T1548 Abuse Elevation Control, Cloud role abuse

• Defense Evasion: T1078 Valid Accounts, T1112 Reg/Policy Changes, T1562 Impair Defenses

• Credential Access: T1556 Modify Auth Process, T1550 Use of Web Tokens/Cookies

• Discovery/Lateral: T1087 Account Discovery, T1021 Remote Services, T1526 Cloud Discovery

• Exfiltration/Impact: T1567 Exfil via Web Services, T1486 Data Encrypted for Impact

Hardening blueprint (priority-ordered)

1) Identity & SSO

• Enforce FIDO2/passkeys for admins and all high-risk apps; block legacy/basic auth.

• Conditional Access: device + location + risk for token issuance; step-up on privilege.

• Admin consent workflow; allow only verified publishers; govern OAuth scopes.

• Rotate and age-limit service-principal secrets, PATs, API keys; prefer managed identities.

• Session policies: short refresh token lifetimes, continuous access evaluation, token binding where available.

2) Cloud & SaaS

• Adopt least-privilege by design: remove “:”; break-glass accounts with HSM-backed keys.

• Just-In-Time (JIT) elevation via PIM/Access Approval; deny standing admin.

• Guardrails: SCPs/organization policies (AWS/GCP), Azure blueprints, OPA/Gatekeeper for K8s.

• Network egress policy for admin subnets; restrict outbound to IdP, patch repos, ticketing, and known AI endpoints.

3) Endpoint & RMM

• Attack Surface Reduction (ASR) rules: block Office child processes, script abuse, credential theft.

• Constrain PowerShell to Constrained Language Mode for standard users; log ScriptBlock.

• Maintain a golden list of RMM tools and managed tenants; block everything else.

4) Email & BEC defenses

• DMARC reject, DKIM/SPF aligned; external sender tag + VIP warning banners.

• Payment change controls: dual-control + out-of-band voice callbacks (with code words).

5) AI/Agent stack (new battleground)

• Tool allow-lists per agent; deny by default.

• Store agent secrets in a vault with short TTL; rotate on pipeline deploy.

• Sign and track RAG corpora updates; enforce data lineage approvals.

Detection engineering: ready-to-use queries & rules

Tailor table names/fields to your platform; intent is practical patterns.

Microsoft Entra ID / M365 (KQL – Log Analytics)

New risky OAuth consent / app role assignment

AuditLogs
| where OperationName in ("Consent to application", "Add app role assignment grant")
| extend Actor = tostring(InitiatedBy.user.userPrincipalName),
        App   = tostring(TargetResources[0].displayName),
        Scopes = tostring(parse_json(tostring(AdditionalDetails))[0].value)
| where Actor !in ("<expected-automation>@yourorg.com")
| project TimeGenerated, Actor, App, Scopes, Result

Impossible/rare sign-ins for admins

SigninLogs
| where Identity in ("global-admin1@yourorg.com","global-admin2@yourorg.com")
| summarize cnt=count(), Countries=make_set(LocationDetails.countryOrRegion)
    by bin(TimeGenerated, 1d), Identity
| where array_length(Countries) > 1

Token minting spikes

IdentityLogonEvents
| summarize tokens=count() by bin(TimeGenerated, 15m), UserId
| join kind=inner (IdentityInfo) on UserId
| where tokens > 3 and AccountRiskLevel in ("medium","high")

Google Workspace (BigQuery – Admin logs)

New third-party OAuth client with broad scopes

SELECT
  protopayload_auditlog.authenticationInfo.principalEmail AS actor,
  protopayload_auditlog.servicedata.@type AS type,
  timestamp
FROM `logs.workspace_admin_*`
WHERE protopayload_auditlog.methodName="google.login.oauth.AddClient"
  AND ARRAY_LENGTH(REGEXP_EXTRACT_ALL(protopayload_auditlog.servicedata_json, "(gmail|drive|admin)")) > 0

AWS CloudTrail (CloudWatch Logs Insights)

AssumeRole from unusual ASN/Geo without MFA

fields @timestamp, userIdentity.sessionContext.sessionIssuer.arn as role, sourceIPAddress, userAgent
| filter eventName="AssumeRole" and ispresent(additionalEventData.MFAUsed)=false
| stats count() by role, sourceIPAddress, userAgent, bin(1h)

Key creation outside pipeline accounts

fields @timestamp, userIdentity.arn as actor, requestParameters.userName
| filter eventName="CreateAccessKey"
| filter not like(actor, /ci-cd|automation/)

GCP (Logs Explorer)

Service account key creation

protoPayload.methodName="google.iam.admin.v1.CreateServiceAccountKey"
resource.type="iam_service_account"

Sigma (Windows – LOLBins burst)

title: LOLBins Execution Burst (Malware-Free)
logsource: { product: windows, category: process_creation }
detection:
  sel:
    Image|endswith:
      - '\powershell.exe' 
      - '\wmic.exe'
      - '\psexec.exe'
      - '\bitsadmin.exe'
  condition: sel
fields: [Image, CommandLine, ParentImage, User]
level: high

Threat hunting playbook (24/72 hours)

Day 0: Contain

• Suspend risky sessions in IdP; revoke refresh tokens; disable new consents temporarily.

• Quarantine high-risk OAuth apps and service principals; rotate secrets.

• Block RMM domains except your approved list.

Day 1: Scope

• Build an identity-centric timeline: who logged in, from where, which apps, what tokens minted, what consents granted.

• Enumerate lateral paths: assume-role chains, kube contexts, SMB shares, SQL linked servers.

• Snapshot cloud IAM for diff-analysis (before/after privileges).

Day 2–3: Eradicate & recover

• Reset trust anchors: SSO signing certs (if suspected), CI/CD credentials, package registries.

• Enforce JIT admin; deploy ASR rules; restrict egress for admin hosts.

• Add detections for your unique stack (custom OAuth scopes, bespoke admin tools).

Red-team simulation ideas (to verify readiness)

• Consent storm: Submit a benign OAuth app and test your admin-consent workflow and detections.

• AitM cookie replay: Attempt SSO session theft against a decoy; validate token revocation speed.

• Service principal pivot: Start from a low-priv SPN and attempt policy abuse to reach data stores.

• RMM misuse drill: Use approved RMM to move laterally; confirm EDR + SIEM highlight operator behavior.

KPIs & board metrics

• % of workforce and 100% of admins on phishing-resistant MFA.

• Mean time to revoke risky OAuth consents or tokens (<60 minutes).

• % of privileged actions performed under JIT elevation (>95%).

• of malware-free detections per quarter caught pre-impact (should trend up).

• % of RMM tools allow-listed and monitored (target: 100%).

The CyberDudeBivash action checklist

• Turn on admin consent workflow + verified publishers only.

• Enforce FIDO2/Passkeys for all admins & service accounts; block legacy auth.

• Kill standing admin; enable PIM/JIT everywhere (cloud + SaaS).

• Ship the detection queries above to your SIEM; alert on first seen OAuth scopes.

• Lock egress from admin hosts; allow only business-critical and monitored endpoints.

• Deploy ASR rules + PowerShell CLM; maintain a strict RMM allow-list.

• Add agent/AI tool allow-lists; vault all secrets with short TTL.

Author: CyberDudeBivash
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Links: cyberdudebivash.com | cyberbivash.blogspot.com

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