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Deep-Dive · 2025 · ToddyCat APT · Internal Threat · Collaboration Espionage

ToddyCat APT Is Inside Your Slack/Teams. Why Your Perimeter Defenses Failed. (A CISO’s Guide to Hunting the Internal Threat)

The ToddyCat APT (Advanced Persistent Threat) has evolved its strategy, moving beyond external firewalls to compromise internal collaboration platforms like Slack and Teams. This attack leverages Trusted Access and stolen sessions to establish persistent, unmonitored espionage, bypassing EDR (Endpoint Detection and Response) and DLP (Data Loss Prevention). The defense must shift from monitoring the network edge to continuous Behavioral Hunting within the application layer.

ByCyberDudeBivash· Founder, CyberDudeBivash Pvt Ltd ThreatWire Deep-Dive ·

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SUMMARY – ToddyCat APT: Internal Espionage and Collaboration Compromise

The ToddyCat APT TTP targets Slack, Teams, or similar collaboration platforms to gain a persistent, internal foothold, treating the internal chat as their new C2 (Command & Control) channel.
The compromise is often achieved via Session Hijacking (stolen M365/SaaS tokens) or malicious file upload (e.g., LNK/JS files) delivered through the trusted internal chat.
The attack bypasses Firewalls and DLP because the C2 communication is disguised as legitimate, whitelisted chat traffic.
CyberDudeBivash Fix: MANDATE FIDO2 Hardware Keys. Implement Behavioral MDR to hunt for Anomalous API Usage and deploy SessionShield for post-hijack termination.

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2. Kaspersky EDR – Trust Monitoring Layer

Essential for hunting the Teams/Slack -> PowerShell pivot (Trusted Process Hijack). Deploy Kaspersky EDR for Telemetry →

3. AliExpress – FIDO2 Keys & Secure MFA

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4. Edureka – Training/DevSecOps Mandate

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1. Phase 1: The ToddyCat TTP – Collaboration Platforms as the Internal C2

The ToddyCat APT (Advanced Persistent Threat) is one of the most sophisticated groups targeting corporate espionage and IP (Intellectual Property) theft. Their TTP (Tactics, Techniques, and Procedures) has evolved beyond exploiting external network flaws to focusing on internal compromise by weaponizing collaboration platforms like Slack, Microsoft Teams, and other internal communication tools.

1.1 The Core Flaw: Trusted Platform for Malicious Delivery

The attack exploits the Trusted Access and implicit trust users place in internal communication.

Perimeter Bypass: The attacker first gains access to a single low-privilege internal account (e.g., via Infostealer or Credential Stuffing). They use this account to deliver the malicious payload internally via chat, bypassing Secure Email Gateways (SEG) and Cloud WAFs (Web Application Firewalls).
Malicious Delivery: The payload is often a fileless LNK/JS file or a malicious image/document containing an RCE (Remote Code Execution) exploit delivered through the file-sharing feature of the chat application.
Internal C2: The attacker then uses the compromised Slack/Teams environment as their internal Command and Control (C2) center, issuing commands and exfiltrating data via whitelisted chat API traffic.

1.2 The EDR and DLP Blind Spot

The ToddyCat TTP is specifically designed to evade conventional security controls.

EDR (Endpoint Detection and Response) Failure: The malware (e.g., a fileless PowerShell script) is executed by a Trusted Process (Teams.exe or Slack.exe), which is whitelisted for file sync and scripting. The EDR ignores the anomalous shell spawning.
DLP (Data Loss Prevention) Failure: The final Data Exfiltration is conducted over encrypted HTTPS using the chat client’s API to the external C2. The traffic is seen as benign chat activity, bypassing DLP content inspection.

2. Phase 2: The Attack Chain -From Malicious File Drop to Session Theft

The ToddyCat kill chain moves from initial internal access to Session Hijacking and Lateral Movement (MITRE T1021).

2.1 Stage 1: Trusted Delivery and Fileless RCE

The attacker sends a malicious file (e.g., an LNK shortcut disguised as a PDF or an embedded link) to a target user via Slack/Teams. The user clicks the file.

RCE Execution: The payload forces the endpoint to execute a LotL (Living off the Land) command: Teams.exe $\rightarrow$ powershell.exe -enc [PAYLOAD].
Credential Dumping: The attacker gains a fileless shell and immediately attempts to steal M365 session cookies and VPN tokens (T1539).

3. Phase 3: The Perimeter Defense and DLP Blind Spot Failure Analysis

The ToddyCat TTP confirms the failure of traditional perimeter security against internal compromise.

3.1 The Firewall/DLP Evasion

The attacker exploits the firewall’s whitelisting of the collaboration platform.

Trusted Traffic: The Firewall and Web Proxy are configured to allow all traffic to *.slack.com or *.microsoft.com (Teams). The attacker uses the chat application’s API to tunnel C2 commands and stolen data through this whitelisted channel.
Insider Access: Once a single account is compromised, the attacker is already operating *inside* the perimeter, rendering the firewall useless.

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4. Phase 4: The Strategic Hunt Guide – IOCs for Internal Pivot and File Drops

The CyberDudeBivash mandate: Hunting ToddyCat requires immediate focus on Process Telemetry and API Log Analysis (MITRE T1059, T1573).

4.1 Hunt IOD 1: Anomalous Shell Spawning (The RCE Signal)

The highest fidelity IOC (Indicator of Compromise) is the chat application spawning a shell.

-- EDR Hunt Rule Stub (High Fidelity Collaboration RCE):
SELECT * FROM process_events
WHERE
parent_process_name IN ('Teams.exe', 'Slack.exe', 'Discord.exe')
AND
process_name IN ('powershell.exe', 'cmd.exe', 'bash', 'nc.exe')

4.2 Hunt IOD 2: Anomalous API Usage and Data Egress

Hunt for Mass Downloads and Chat Tunneling in application logs (T1573).

API Log Hunt: Alert on excessive API calls from a single user attempting to retrieve message history or download files outside of normal bounds.
Network Flow Hunt: Monitor for DNS/Network Tunneling activity on the compromised endpoint, or encrypted HTTPS traffic directed to the collaboration API that is anomalously high volume (indicating data exfil).

5. Phase 5: Mitigation and Resilience – CyberDudeBivash Segmentation Mandate

The definitive defense requires immediate patching combined with architectural segmentation (MITRE T1560).

5.1 Application Control (The Execution Killer)

You must prevent the compromised collaboration application from executing any secondary shell process.

WDAC/AppLocker: Enforce a policy that explicitly blocks the collaboration application process (Teams.exe or Slack.exe) from spawning shell processes (powershell.exe, cmd.exe).
File Transfer Restriction: Configure policies to **block** the upload/download of high-risk file types (.LNK, .JS, .VBS) within the collaboration environment.

6. Phase 6: Architectural Hardening – Application Control and FIDO2 Deployment

The CyberDudeBivash framework mandates architectural controls to contain the damage of a successful compromise.

Mandate FIDO2: Enforce Phish-Proof MFA (FIDO2 Hardware Keys) for all collaboration logins, neutralizing the Session Hijacking threat that targets M365/SaaS access.
SessionShield Deployment: Deploy SessionShield for continuous monitoring of user sessions. SessionShield detects and instantly terminates an anomalous login that follows the compromise.
Network Segmentation: Isolate collaboration servers and limit their egress to only necessary API endpoints (e.g., block direct connection to public file hosting services).

7. CyberDudeBivash Ecosystem: Authority and Solutions for Internal Threat Hunting

CyberDudeBivash is the authority in cyber defense because we provide a complete CyberDefense Ecosystem designed to combat the ToddyCat APT.

Managed Detection & Response (MDR): Our 24/7 human Threat Hunters specialize in monitoring the EDR telemetry for the Trusted Process Hijack (Teams.exe -> powershell.exe) and anomalous API usage.
PhishRadar AI: Proactively blocks AI-driven spear-phishing and malicious file lures delivered via email and internal messaging.
Adversary Simulation (Red Team): We simulate the ToddyCat kill chain against your internal chat environment to verify your Application Control and File Transfer security policies.

8. Expert FAQ & Conclusion

Q: Why did my firewall fail against this APT?

A: The firewall fails because the attack leverages Trusted Access. It allows traffic to *.slack.com or *.microsoft.com. The attacker exploits this whitelisted connection to tunnel C2 commands and stolen data, bypassing the firewall’s perimeter inspection entirely.

Q: How does the malware execute via Slack/Teams?

A: The malware executes via a Trusted Process Hijack. A malicious file (e.g., a simple LNK file disguised as a PDF) is shared. When the user clicks it, the collaboration app process (e.g., Teams.exe) is forced to spawn a LotL shell (powershell.exe), which is logged as low-severity noise by EDR.

Q: What is the single most effective defense?

A: Application Control and FIDO2 MFA. Enforce WDAC/AppLocker to block the collaboration app from spawning any shell process. This breaks the RCE kill chain. Simultaneously, mandate FIDO2 Hardware Keys to neutralize stolen session tokens.

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12. Related Posts & Next Reads from CyberDudeBivash

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