Inside the Keylogging Fusion: Analyzing North Korea’s New ‘BeaverTail & OtterCookie’ Malware Combination

CYBERDUDEBIVASH • ThreatWire

Published: October 17, 2025

Inside the Keylogging Fusion: Analyzing North Korea’s New “BeaverTail & OtterCookie” Malware Combinationwww.cyberdudebivash.com•cyberdudebivash-news.blogspot.com•cyberbivash.blogspot.com•cryptobivash.code.blogBeaverTail — Low-noise Keylogger OtterCookie — Browser Token/Cookie Theft SSO / JWT C2 • Proxy Relay / Dead Drop“BeaverTail” captures keystrokes while “OtterCookie” steals session tokens/cookies; both trickle data to proxy C2 for account takeover and lateral movement.

TL;DR: A North Korea–aligned cluster is pairing a quiet user-mode keylogger (“BeaverTail”) with a token/cookie stealer (“OtterCookie”). The combo evades MFA by hijacking active sessions, then replays stolen cookies to access email, Git, CI/CD and cloud consoles. Initial access: malicious Office docs, package manager scripts, and IT support lures. Priority: invalidate tokens, rotate SSO secrets, hunt for browser data exfil, and enforce device-bound MFA.

Focus regions: US • EU • UK • AU • IN • Targets: Media, Crypto/FinTech, Defense-adjacent R&D, IT MSPs/MSSPs

Executive Summary

Instead of brute-forcing MFA, the operators harvest what MFA protects—your already-validated browser state. By combining keystrokes (credentials, seed phrases, CLI tokens) with live cookies (SSO/JWT/SessionID), they jump straight into mailboxes, source repos, ticketing, and cloud admin portals. Expect hands-on-keyboard follow-ups and selective data theft to sustain access.

Probable Attack Chain

Initial Access — Malicious Office/ISO/zipped JS; staged via drive-by, spear-phish, or fake helpdesk chats. Some samples use signed-but-abused installers or LOLBins (wscript, mshta, rundll32).
Execution — User-space loader drops “BeaverTail” (DLL/EXE) and a lightweight “OtterCookie” module (per-browser grabber).
Persistence — Run keys, scheduled tasks, WMI subscriptions; optional Edge/Chrome extensions for refresh-proof session access.
Discovery & Collection — Keystrokes + clipboard; export Cookies/Login Data DBs, localStorage, extension vaults.
Exfiltration — HTTPS to rotating C2, paste/notes dead-drops, or commodity file hosts; optional DNS canary trickle.
Post-Exploitation — Cookie replay to Outlook/Teams/Slack/Jira/Git; creation of PATs, OAuth app grants, admin role sprawl.

Technical Traits (What to Look For)

BeaverTail: low-rate file writes to obfuscated paths, event hooks via SetWindowsHookEx, rare ETW tamper; sleeps/jitters to blend with user activity.
OtterCookie: copies Chromium profiles (%LOCALAPPDATA%\[Browser]\User Data\), decrypts with DPAPI; grabs Cookies, Login Data, Web Data, and app tokens.
Defense evasion: signed loader; LOLBins for staging; encrypted config blobs with domain allowlists; proxy-aware beaconing.
C2 patterns: short-lived domains behind CDN/fronting, rotating TLS prints; URIs that mimic telemetry.

Detections that Actually Fire

EDR / Sysmon
- Event hooking: SetWindowsHookEx from unknown signer → ALERT
- Abnormal reads of leveldb/SQLite in browser profile by non-browser process
- DPAPI decrypt shortly after browser shutdown
- New Scheduled Task / WMI subscriptions with random animal/day names
- Mass PAT creation in GitHub/GitLab/Azure DevOps within 60m of atypical login

Identity / SIEM
- Impossible travel + cookie replay (no fresh MFA) to M365/Jira/Confluence
- Spike in OAuth consent grants or new enterprise app registrations

Network
- Small periodic HTTPS POSTs (

Rapid Response Playbook (60–180 minutes)

  Contain: Isolate hosts; block C2 FQDN/IP; revoke OAuth grants & PATs; disable suspicious extension IDs.
  Invalidate Sessions: Force re-auth on IdP; revoke refresh tokens org-wide; rotate session keys/secrets.
  Hunt: Query for DPAPI access on browser stores; non-browser reads of Cookies/Login Data; new tasks/WMI.
  Credential Hygiene: Reset user pwds; rotate app secrets; require device-bound passkeys for privileged roles.
  Eradicate: Remove persistence; uninstall rogue extensions; reimage high-risk admin/dev machines if needed.
  Hardening: Conditional Access (device compliance + MFA), short session life, CAE, disable legacy protocols.


For Your SOC: Practical Queries (Examples)
Windows (pseudo-KQL)
DeviceProcessEvents
| where FileName in~ ("rundll32.exe","wscript.exe","mshta.exe")
| where ProcessCommandLine has_any ("User Data\\Default\\Cookies","\\Login Data","localstorage")

DeviceFileEvents
| where FolderPath has "\\User Data\\Default\\"
| where InitiatingProcessFileName !in~ ("chrome.exe","msedge.exe","brave.exe")

OAuth/PAT audit
AuthZGrant
| where NewConsent == true or Scopes has_any ("Mail.ReadWrite","offline_access")
| summarize count() by UserId, AppId, bin(1h)


IOC & Telemetry (Populate During IR)

  Filenames/Paths: user-profile temp dirs with animal-theme names; %APPDATA%\Microsoft\<random>\*.log slowly growing.
  Mutexes: simple words (“btail”, “otter”), day-based tokens.
  C2: newly registered domains; subdomains resembling analytics/telemetry.
  Hashes: case-specific; expect rapid re-packing → do not rely on static IOCs.



Who’s in the Crosshairs?

  US/EU media & tech: newsroom accounts → social hijack + data theft.
  UK/AU MSP/MSSP: shared admin workstations → downstream client compromise.
  IN crypto/fintech: wallet seed/keystroke theft + SSO cookie replay → instant takeover.



Related Reading on CyberDudeBivash

  Keylogger case studies & detections
  Cookie theft & token replay defenses
  Stopping OAuth app abuse in the enterprise



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  APT, DPRK, keylogger, cookie theft, session hijacking, MFA bypass, OAuth abuse, DPAPI, Chromium profiles,
  Sysmon, EDR, SIEM, identity security, OAuth consent, passkeys, conditional access, US, EU, UK, Australia, India.




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Educational, defensive guidance only. Indicators above are representative; validate against your telemetry and current advisories before enforcement.

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