Source: Help Net Security Author: Help Net Security URL: https://www.helpnetsecurity.com/2025/02/24/botnet-hits-microsoft-365-accounts/
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ONE SENTENCE SUMMARY:
A massive botnet of 130,000 devices is launching stealthy password-spraying attacks on Microsoft 365 accounts, bypassing traditional security defenses. -
MAIN POINTS:
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A newly discovered botnet is conducting large-scale password-spraying attacks on Microsoft 365 accounts.
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SecurityScorecard researchers suspect links to China-affiliated threat actors based on hosting infrastructure evidence.
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The attack exploits Non-Interactive Sign-Ins to evade traditional security controls and MFA defenses.
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Targeted industries include financial services, healthcare, government, technology, and education.
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The botnet uses command-and-control servers hosted by SharkTech, known for previous malicious activity.
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Non-Interactive Sign-Ins allow attackers to avoid triggering account lockouts or security alerts.
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Organizations with strong security measures may still be vulnerable due to gaps in authentication logging.
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Potential nation-state involvement raises concerns about espionage and data exfiltration risks.
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Security teams should review logs, rotate credentials, disable legacy authentication, and monitor for stolen credentials.
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Microsoft plans to retire Basic Authentication by September 2025, increasing urgency for stronger authentication methods.
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TAKEAWAYS:
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Password-spraying attacks are evolving to bypass traditional security measures like MFA and Conditional Access Policies.
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Non-Interactive Sign-Ins present a critical security blind spot that attackers are actively exploiting.
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Organizations relying on Microsoft 365 must enhance authentication monitoring and security controls.
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Nation-state actors may be leveraging this attack for espionage and data theft.
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Transitioning away from legacy authentication methods is crucial before Microsoft’s 2025 deadline.