Beware: Malicious OAuth Apps Pose as Adobe and DocuSign to Target Microsoft 365 Users

TL;DR

Cybercriminals are utilizing malicious Microsoft OAuth apps disguised as Adobe and DocuSign to steal Microsoft 365 credentials and distribute malware.

Malicious OAuth Apps Targeting Microsoft 365 Accounts

Cybercriminals have launched a new campaign using malicious Microsoft OAuth apps that mimic Adobe and DocuSign. These fraudulent apps aim to steal Microsoft 365 account credentials and deliver malware. This sophisticated attack leverages the trust users have in well-known brands to bypass security measures.

Understanding the Threat

The attack involves several steps:

1. Phishing Emails: Users receive phishing emails that appear to be from Adobe or DocuSign.
2. Malicious Links: These emails contain links that direct users to fake OAuth apps.
3. Credential Theft: Once users grant permission, their Microsoft 365 credentials are compromised.
4. Malware Delivery: In addition to stealing credentials, these apps can also install malware on the user’s device.

Impact and Risks

This attack poses significant risks:

• Data Breach: Compromised credentials can lead to unauthorized access to sensitive information.
• Malware Infection: Devices can be infected with malware, leading to further data theft or system damage.
• Reputation Damage: Organizations may suffer reputational harm if their accounts are used for malicious activities.

Protective Measures

To safeguard against these threats, consider the following steps:

• User Education: Train users to recognize phishing attempts and avoid clicking suspicious links.
• Multi-Factor Authentication (MFA): Implement MFA to add an extra layer of security.
• Regular Updates: Keep all software and security tools up to date.
• Monitoring: Use monitoring tools to detect and respond to unusual activities.

Conclusion

The rise of malicious OAuth apps disguised as trusted brands underscores the need for vigilance and proactive security measures. By staying informed and implementing robust security practices, users and organizations can mitigate the risks associated with these evolving threats.

For more details, visit the full article: source¹

References

1. (2025, March 16). “Malicious Adobe, DocuSign OAuth apps target Microsoft 365 accounts”. BleepingComputer. Retrieved 2025-03-16. ↩︎