Is slack secure? Redact sensitive slack messages!

Is Slack secure for your business?

Slack is a cornerstone of many companies' workplace technology solutions. Particularly with more companies working in a remote or hybrid setting, or even companies working between multiple locations, Slack is indispensable to their daily operations. However, the more information companies put in a Slack workspace, the greater their risk in the event of a data breach. Think of the most recent Uber Data breach because an employee's slack credentials were compromised due to a phishing scam.

Common types of sensitive data shared very often in slack are:

1. Credit card numbers and confidential financial data
2. Customer sales data
3. Sensitive PHI (Protected Health Information)
4. Customer PII
5. API Keys
6. Confidential files in the forms of PDFs, Images, HARs, XLSX ,google docs and Word document

✨What type of sensitive data can be found in Slack?

Sensitive data in Slack appears more often than organizations expect because Slack is used daily for chats, file sharing, tickets, approvals, and quick decision-making workflows. This makes Slack a high-velocity environment where employees unintentionally paste confidential information, customer details, or internal documents. Understanding what type of sensitive data can be found in Slack is essential for improving security, reducing leak risks, and supporting compliance requirements in regulated industries.

Below are the most common sensitive data types found inside Slack:

PII and employee information

Names, phone numbers, home addresses, emails, IDs, social security numbers, CVs, payroll details, onboarding documents.

Customer data and support information

Support conversations, case details, screenshots, financial information, personal complaints, uploaded attachments containing PII or PHI.

Financial and payment data

Invoices, credit card details, payment confirmations, bank account data, vendor contracts, pricing sheets.

Credentials and internal secrets

API keys, access tokens, passwords, SSH keys, GitHub credentials, AWS keys accidentally pasted into chats or shared in private channels.

Product and engineering data

Internal roadmaps, architecture diagrams, database exports, test data with PII, CSVs, error logs containing sensitive fields.

Healthcare or regulated data

PHI for healthtech companies, HIPAA-sensitive logs, patient identifiers, lab reports, medical consultations.

When sensitive information enters Slack, the risk spreads quickly because that data can get copied, forwarded, downloaded, indexed, or synced into other systems. This is why organizations use Strac to automatically discover, classify, and redact sensitive data in Slack so exposure cannot expand further.

Low-Hanging Fruits in Slack Sensitive Data Security Features

One of the main concerns with using Slack is the risk of data breaches. Slack is a cloud-based service, which means that data is stored on remote servers. While Slack has implemented various security measures to protect data, including encryption and two-factor authentication, it is still vulnerable to cyber attacks.

1. Enable Two-Factor Authentication

‎As is recommended for all services, setting up two-factor authentication is a simple yet powerful way to protect against bad actors seeking to log in with your credentials. Slack supports most time-based, One-Time Password (TOTP) applications you may already be using, such as Duo Mobile, 1Password, Microsoft Authenticator, Google Authenticator, and more.

2. Making channels private

‎You can set permissions on an individual channel to further protect sensitive information. Making a channel "private" prohibits members from seeing the channel unless they are invited. This feature is great for channels in which sensitive information may be discussed. For example, a board of directors channel discussing high-level information may be best kept private.

3. Limit Access To Workspace

Security's best practice is to grant access to employees or guests only when they need to be part of a slack channel or workspace. It is best practice to revoke access once the business function is done.

Are There Any Security & Compliance Risks that are not Solved in Slack?

Even with solid security practices, like two-factor authentication and limiting access to who needs it, sharing customers' most sensitive information or businesses' confidential secrets/keys is still risky over Slack.

1. There is no way to prevent employees from sending sensitive data like Drivers licenses, identity pictures, SSNs, bank statements OR even API Keys/secrets/private keys. There is a massive risk of data loss exfiltration.
2. Slack has different channels: public, private, DM (Direct Message), and Group DM. These channels allow employees to share sensitive data making it harder for IT and Security auditors to oversee what information is shared.
3. There is no way for the business to implement GDPR or CCPA's Right To Delete control as data is all over the place for a customer.

Top Slack privacy concerns

Slack privacy concerns arise because Slack operates as a centralized knowledge hub where employees communicate rapidly across channels, threads, DMs, and integrated apps. This constant flow of information increases the likelihood of oversharing sensitive data, misconfigured settings, or unauthorized access to files and messages. Understanding the top Slack privacy concerns helps organizations put the right controls in place before a data leak or compliance incident occurs.

Here are the most pressing Slack privacy concerns:

1. Sensitive data shared in messages and files
Employees frequently paste PII, credentials, financial data, or customer information into Slack without realizing it. These messages persist unless automatically redacted or removed.

2. Overexposed public or shared channels
Teams often create public channels by default. Sensitive discussions or file uploads end up visible to more employees than intended.

3. Third-party Slack apps with broad permissions
Integrations often request access to messages, file contents, or metadata. Poorly governed apps increase the risk of unauthorized data exposure.

4. Lack of visibility into historical data
Slack stores years of messages and file history. Organizations often have no idea what sensitive information already exists in their Slack workspace.

5. External collaborators and guest users
Agencies, contractors, or freelancers may gain access to internal channels. Misconfigured roles or permission drift can lead to unintended data visibility.

6. Screenshots and attachments exposing confidential details
Screenshots of dashboards, medical portals, CRMs, or financial systems often contain hidden PII or PHI.

7. Manual review processes that miss risky content
Security teams cannot manually scan tens of thousands of messages per day. Slack needs automated detection and redaction to prevent exposure in real time.

These privacy concerns compound over time as Slack grows into the central communication tool for the entire organization. Strac helps eliminate these risks by detecting and redacting sensitive data, enforcing security policies, and giving teams visibility into what data lives inside Slack so privacy issues are resolved before they become incidents.

✨Modern Data Loss Prevention (DLP) Solution

Strac's Data Loss Prevention (DLP) Solution for Slack Free, Pro, Business and Enterprise plans automatically detects and redacts (masks) sensitive data like PII (SSN, DL, Passport, etc.), PHI (patient data, dob, etc.), credit card numbers, bank account details, API keys, and more from Slack messages.

Below is a sample list of sensitive data elements that will be detected & redacted in Slack workspace:

• Identity: Drivers License, Passport, SSN (Social Security Number), National Identification Number, etc.
• PII: Name, Address, Email, Phone, DoB, Age, Gender, Ethnicity, etc.
• PHI: PII data, Medical Record Number (MRN), Insurance ID, Health Plan Beneficiary Number, Biometric, Medical Notes, etc.
• Payments: Bank Account, Routing Numbers, Credit Card, Debit Card, IBAN, etc.
• Secrets: API Keys, Passwords, Passphrases, etc.
• Vehicle: License Plate, Vehicle Identification Number (VIN), etc.
• Physical Network: IP Addresses, MAC Address, etc.
• Crypto Secrets: Seed Phrase, Bitcoin, Ethereum, Litecoin Addresses, etc.
• Profanity: Curse words, abuse words, etc.
• Custom: Create your own rules or use regex

Strac's Redactor is powered by its Machine Learning models that help businesses comply with PCI, HIPAA, SOC2 and various privacy laws by automatically redacting sensitive data. Strac also exposes REST APIs for redacting (or masking) any data.

Bottom Line

Slack is a powerful collaboration platform, but its speed and volume of communication create real risks when sensitive data enters channels, DMs, and file uploads. Native Slack security protects the platform; it does not automatically protect the content users share every day. Pairing Slack with Strac gives organizations real-time visibility, automated redaction, and continuous protection, making Slack not only secure but truly safe for handling PII, PHI, PCI, secrets, and confidential business information.

🌶️Spicy FAQs About Slack Security

Does Slack have good security?

Slack offers strong baseline security, especially when organizations configure access, retention, and authentication correctly. Its encryption, compliance certifications, and admin controls make it a reliable platform for collaboration. However, Slack’s native security does not automatically prevent users from sharing sensitive data in messages and files.

Key points:

• Strong encryption in transit and at rest.
• Supports SSO, SAML, MFA, Enterprise Key Management, and audit logs.
• Compliance-ready on higher tiers: SOC 2, ISO, FedRAMP Moderate, and more.
• Does not detect or redact sensitive data inside messages.
• Slack security is solid, but it needs DLP and automated oversight to fully protect sensitive information.

What are the security concerns of Slack?

Slack becomes risky when users overshare information or when settings are not properly configured. Most risks come from human behavior and the speed of communication rather than the platform itself. Identifying the main concerns helps teams close the gaps quickly.

Top concerns:

• Employees paste PII, financial data, credentials, or PHI into channels.
• Public channels reveal more information than intended.
• Third party apps often request broad access to messages and files.
• Guest accounts and contractors may retain access longer than expected.
• Long-term retention means years of sensitive content remain searchable.
• The biggest security issue is visibility; without automated DLP, sensitive data spreads silently.

Is Slack secure enough for HIPAA compliance?

Slack can support HIPAA compliance, but only when used on the correct plan and with strict controls. Not all Slack environments qualify automatically. Healthcare organizations must combine Slack’s enterprise features with additional safeguards for PHI.

HIPAA considerations:

• Requires Enterprise Grid and a signed BAA.
• Admins must enforce tight retention, MFA, and controlled exports.
• Slack does not natively detect or redact PHI.
• Manual oversight is not enough for high-volume clinical teams.
• To achieve real HIPAA compliance, organizations use Slack + Strac to automatically detect and redact PHI across messages and files.

Can Slack messages be intercepted?

Slack encrypts data in transit and at rest, which prevents typical network-level interception. However, interception risks shift to endpoints, account access, and app permissions. Understanding where exposure is possible helps reduce the likelihood of message misuse.

Where interception risks exist:

• Compromised user accounts or stolen devices.
• External apps with message-reading permissions.
• Admin export tools on certain Slack plans.
• Screenshots, copy-paste, or file downloads by internal users.
• Slack protects network-level transmission well, but endpoint and access controls remain critical.

How does Slack protect sensitive data?

Slack provides strong platform-level protections but does not classify or control what users share. Its native features help secure access, manage content, and enforce compliance policies. Sensitive data still travels freely unless external DLP tools are added.

Slack protections include:

• Encryption at rest and in transit.
• MFA, SSO, granular permissions, and enterprise device controls.
• Audit logs, workspace monitoring, and message retention rules.
• Enterprise Key Management for additional control.
• Slack handles the platform security; Strac handles the data security by detecting and redacting sensitive content directly inside Slack.