Hackers Use Corrupted ZIPs and Office Docs to Evade Antivirus and Email Defenses

Hackers Use Corrupted ZIPs and Office Docs to Evade Antivirus and Email Defenses

December 4, 2024 at 12:45AM

A new phishing campaign uses corrupted Microsoft Office documents and ZIP files to bypass email defenses, evading antivirus software and spam filters. These malicious emails entice users with false promises, leveraging built-in recovery features for execution. The technique, identified since August 2024, aims for credential theft and malware deployment.

**Meeting Takeaways – Dec 04, 2024**

1. **New Phishing Campaign**: Researchers have identified a novel phishing scheme utilizing corrupted Microsoft Office documents and ZIP files to bypass email security measures.

2. **Bypassing Security**: The campaign is designed to evade antivirus software, sandbox uploads, and Outlook’s spam filters, allowing harmful emails to reach user inboxes.

3. **Malicious Attachments**: Emails contain deliberately corrupted attachments that are not flagged as harmful, tricking users into opening them with misleading promises about employee benefits.

4. **Exploitation of Recovery Features**: Attackers exploit the recovery mechanisms of Microsoft programs (like Word and Outlook) and WinRAR that allows the damaged files to be reopened, which can lead to malicious outcomes.

5. **Zero-Day Vulnerability**: This technique has been in use since at least August 2024 and is described as a potential zero-day exploit, highlighting the evolving tactics of cybercriminals.

6. **Deceptive Tactics**: Once a user opens a compromised document, it may contain QR codes, redirecting them to fraudulent sites aimed at malware installation or credential theft.

7. **Security Implications**: This emphasizes the ongoing challenge for cybersecurity to detect new and sophisticated phishing techniques, underscoring the need for updated security practices and vigilance among users.

8. **Call for Awareness**: Organizations should enhance user awareness and training to recognize suspicious attachments and links, even when they appear to come from trusted sources.

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