Security researchers have identified a phishing campaign that uses Microsoft Teams messages impersonating IT support staff to distribute a newly discovered malware known as SynkLoader. Read this Cybersecurity Threat Advisory to understand the risks associated with SynkLoader, identify potential exposure, and learn the recommended steps to protect your users and systems.
What is the threat?
SynkLoader is a newly discovered multi-stage malware distributed through Microsoft Teams phishing campaigns. Threat actors impersonate IT support personnel and send convincing messages designed to trick users into downloading and launching malicious files.
Once executed, SynkLoader displays a fake Windows lock screen that prompts users to enter their credentials. Captured credentials can then be used to access user accounts, establish persistence, and facilitate additional malicious activity within the victim environment.
By combining social engineering with credential theft, attackers can gain an initial foothold that may lead to broader network compromise.
Why is it noteworthy?
SynkLoader highlights a growing trend of attackers abusing trusted collaboration platforms such as Microsoft Teams to circumvent traditional email-based security controls. By impersonating IT support staff, threat actors exploit user trust and create a greater sense of urgency, increasing the likelihood of successful compromise.
Because Teams is widely used for daily business communications, malicious messages may appear more legitimate to users and can result in credential theft, unauthorized access, or the deployment of additional malware.
What is the exposure or risk?
Organizations that rely on Microsoft Teams for internal communication may be vulnerable to this attack technique, particularly if users can receive messages from external contacts.
Successful attacks can result in:
- Theft of Windows and corporate account credentials.
- Unauthorized access to business applications and systems.
- Lateral movement to additional devices and users within the environment.
- Deployment of secondary payloads, including ransomware or data-stealing malware.
- Exposure of sensitive business information, intellectual property, and customer data.
Because the attack leverages a trusted collaboration platform, users may be more likely to interact with malicious content than they would through traditional phishing emails.
What are the recommendations?
Barracuda recommends the following actions to reduce the risk of SynkLoader infections and Microsoft Teams-based phishing attacks:
1. Restrict external Teams communications
- Disable or limit external Teams messaging where business requirements allow.
- Review Teams federation settings and restrict communications to trusted organizations.
2. Strengthen identity security
- Enforce multi-factor authentication (MFA) for all user accounts.
- Implement strong password policies and regularly review privileged accounts.
3. Train users to recognize social engineering
- Educate employees on phishing tactics delivered through collaboration platforms.
- Remind users to be cautious of unsolicited IT support requests, software installations, or credential prompts.
4. Verify IT support requests
- Establish a formal process for validating support requests received through Teams.
- Encourage users to confirm unexpected requests through approved IT channels.
5. Enhance endpoint protection and monitoring
- Deploy and maintain endpoint detection and response (EDR) solutions.
- Monitor for suspicious processes, credential theft activity, and unusual user behavior.
6. Review Teams security settings
- Audit Teams configurations and apply Microsoft’s recommended security best practices.
- Regularly review permissions, external access settings, and security policies.
7. Encourage prompt reporting
- Instruct employees to immediately report suspicious Teams messages, unexpected downloads, or credential requests.
- Investigate reports quickly to limit potential impact.
References
For more in-depth information about the recommendations, please visit the following links:
- https://www.bleepingcomputer.com/news/security/new-synkloader-malware-pushed-in-microsoft-teams-phishing-campaign/
- https://cyberexperts.com/2026-08-24-new-synkloader-malware-pushed-in-microsoft-teams-phishing-campaign/
- https://www.pcrisk.com/internet-threat-news/35791-synkloader-malware-spreads-via-fake-teams-it-support-chats
If you have any questions about this Cybersecurity Threat Advisory, don’t hesitate to get in touch with Barracuda Managed XDR’s Security Operations Center.
This post originally appeared on Smarter MSP.