Slack has become seemingly ubiquitous among the workforce. The email disruptor, now owned by Salesforce, serves over 200K paid organizations, including 77 of the Fortune 100. 

As with most solutions that bring enormous value to the enterprise, Slack also introduces material risk, often in the form of data exfiltration that isn’t detected by the SOC. The speed, transparency, and collaboration Slack drives means employees are able to easily and broadly share data—and they do so, often without training or governance guardrails. 

Slack’s strengths become your crisis

A leading risk vector for Slack comes down to fundamentals: an organization’s Identity and Access Management and lateral movement controls. Adversaries who gain access to a user’s device are able to steal identity tokens out of the memory of the machine and then log into Slack to access an organization’s data—bypassing any MFA controls.

Imperfect security controls leave you guessing

Exposure to data exfiltration from Slack—or any other internal application—comes down to  the limits of your defenses. Security posture is not the sum of your tools. It’s the sum of what an attacker can do despite them. 

Without the attacker’s perspective, organizations commonly over-rely on DLPs that typically don’t monitor private messages or group chats—leaving massive exposure. They also place too much faith in EDRs, which rarely provide comprehensive endpoint coverage and are often misconfigured, making them ineffective at detecting Remote Access Tools (RATs). And many still rely on vulnerability scanning tools that can’t identify what an attacker would actually care about in their unique environment.

Compounding the challenge, SOCs typically have less visibility into internal productivity tools like Slack compared to critical infrastructure. But attackers know there are many paths to high value targets.

Offense improves defense: Stop guessing, start proving

The answer is to proactively discover and remediate risk before attackers do. The gold standard for this is penetration testing—but done manually, it’s cost-and time-prohibitive to assess risk across your entire network. To test comprehensively and continuously as environments change, security teams can turn to SaaS pentesting solutions.  

Let’s take a look at one real-world example of a Slack Dump achieved by NodeZero and the chain of weaknesses it used to exfiltrate high-value business data.

Attack chain analysis: 3 critical steps

For CISOs reporting to the board, the Slack Dump scenario isn’t just about tokens—it’s about reputational, legal, and competitive risk. When your internal R&D roadmap, contract details, and credentials are all in Slack, a single compromise can derail the business – Snehal Antani, Horizon3.ai

1. Initial access and RAT deployment

In this example, the user kicked off an internal pentest, so NodeZero starts on a single host with no privileges. From there:

• NodeZero exploits Link-Local Multicast Name Resolution (LLMNR) to spoof network traffic.
• Then, NodeZero uses man-in-the-middle (MITM) techniques to harvest NTLM hashes and successfully cracks a hash into its cleartext password. 
• With that domain user and password pair NodeZero exploits a PrintNightmare vulnerability and deploys a RAT onto that host.

💡EDR solutions should detect this activity but often fails—among dozens of EDR vendors NodeZero encounters, the failure rate for detecting the RAT is often around 20% (with one vendor failing to detect over 90% of the time). 

The learning? Make sure you’re validating your EDR efficacy and tuning as needed to get your money’s worth.

💡EDR solutions should detect this activity but often fails—among dozens of EDR vendors NodeZero encounters, the failure rate for detecting the RAT is often around 20% (with one vendor failing to detect over 90% of the time). 

The learning? Make sure you’re validating your EDR efficacy and tuning as needed to get your money’s worth.

2. Lateral movement to achieve domain admin credentials

• With the RAT, NodeZero dumps sensitive windows processes including SAM and gains access to more interesting credentials. 
• NodeZero uses the compromised creds to move laterally through the network and lands a second RAT on another host. 
• This RAT dumps the Windows Data Protection service (DPAPI), harvesting more credentials—one of which has Domain Admin privileges, which means NodeZero now has keys to the kingdom

3. Slack environment compromise

• With Domain Admin creds, NodeZero moves to a third machine and drops another RAT 
• This RAT extracts Slack authentication tokens directly from the host’s application memory
• Now NodeZero has complete Slack workspace access and can impersonate the user and get private channel access

At this point NodeZero has proven—in production with a real attack—that an adversary could steal any business data this user has access to.

Top security takeaways

This one example from a production environment highlights a number of realities security teams should keep in mind. 

• EDR bypass: Modern RATs can evade detection through obfuscation and signature randomization. 
• MFA limitations: In-memory tokens bypass authentication regardless of MFA implementation
• Detection gaps: Process hollowing and memory manipulation techniques consistently bypass security monitoring
• Data exposure: Slack commonly contains massive amounts of sensitive information (API keys, contracts, PII) making it a high-return target for bad actors. 

Strategies to tighten your defense

First and foremost, you need to test your defenses continuously, at scale. This means looking at your environment through the lens of an adversary looking to achieve a malicious outcome, not compromise any specific weakness or CVE itself.

In this attack path, NodeZero revealed the defensive improvements needed, giving the team specific, high-return actions to take.  

1. Endpoint hardening

• Apply critical Microsoft security updates (i.e. PrintNightmare KB5004945+)
• Disable legacy authentication protocols (LLMNR, NetBIOS)
• Implement proper network segmentation
• Eliminate local administrator privileges for standard users

2. Enhanced Detection

• Implement EDR rules to detect credential harvesting activities (SAM, LSASS, DPAPI)
• Create alerts for proxy patterns that might indicate token abuse

3. Deception Technology

• Deploy honeytokens within Slack (decoy files, channels, and fake API keys)
• Monitor for access to these resources as an early warning system
• Integrate with SIEM systems to reduce detection time from days to minutes

See your unique Slack risk exposure with NodeZero

If you’re ready to know exactly where you’re exploitable, our team is here to give you a personalized demo. With autonomous, scalable attack chaining and proof of exploitation, you’ll be empowered to make better risk tolerance decisions—and evolve them as your attack surface and exposure change.