ZeroFont Phishing: Hackers Manipulating Font Size to Bypass Office 365 Security

A new but ancient technique for Phishing emails has been recently identified called ZeroFont Phishing. Threat actors have followed several tactics for sending phishing emails, bypassing all the security mechanisms.

However, using this technique, threat actors could bypass Microsoft’s Natural Language Processing, which was acting as a Phishing email protection for Office users. 

Office 365 – Natural Language Processing

Microsoft has been working towards their way of securing its customers in all aspects. One of the major areas they focus on is phishing (Business Email Compromise) attacks, which have been the most used technique by threat actors for infiltrating organizations.

To prevent these phishing emails, Microsoft has been relying on Natural Language Processing, which scans the contents of an email for signs of impersonation or fraud. If an email content includes text like “© 2018 Microsoft Corporation. All rights reserved” and the email is not from Microsoft.com, Microsoft immediately flags this email as fraudulent.

This technique was also used to interpret email contents like banking information, user accounts, password resets, and financial requests and are checked for authenticity. However, threat actors bypassed this technique using the ZeroFont Phishing attack.

ZeroFont Phishing

The threat actor sends an email to the victim impersonating an Office 365 quota limit notification, which looks like an administrative service email. However, this phishing email bypassed the protection due to the use of the ZeroFont attack.

ZeroFont Phishing attack (Source: AVANAN)

Threat actors inserted random text inside the email, which had <span style=”FONT-SIZE: 0px”> for a zero font size, and broke up the text strings to bypass Microsoft’s natural language processing. 

Source: Avanan

A complete report has been published by Avanan, which provides detailed information about this attack and bypass scenarios used by threat actors. 

Protect yourself from vulnerabilities using Patch Manager Plus to quickly patch over 850 third-party applications. Take advantage of the free trial to ensure 100% security.

Eswar

Eswar is a Cyber security content editor with a passion for creating captivating and informative content. With years of experience under his belt in Cyber Security, he is covering Cyber Security News, technology and other news.

Recent Posts

LightSpy iOS Malware Enhanced with 28 New Destructive Plugins

The LightSpy threat actor exploited publicly available vulnerabilities and jailbreak kits to compromise iOS devices.…

1 day ago

ATPC Cyber Forum to Focus on Next Generation Cybersecurity and Artificial Intelligence Issues

White House National Cyber Director, CEOs, Key Financial Services Companies, Congressional and Executive Branch Experts…

3 days ago

New PySilon RAT Abusing Discord Platform to Maintain Persistence

Cybersecurity experts have identified a new Remote Access Trojan (RAT) named PySilon. This Trojan exploits…

3 days ago

Konni APT Hackers Attacking Organizations with New Spear-Phishing Tactics

The notorious Konni Advanced Persistent Threat (APT) group has intensified its cyber assault on organizations…

3 days ago

Google Chrome Security, Critical Vulnerabilities Patched

Google has updated its Chrome browser, addressing critical vulnerabilities that posed potential risks to millions…

3 days ago

Notorious WrnRAT Delivered Mimic As Gambling Games

WrnRAT is a new malware attack that cybercriminals have deployed by using popular gambling games…

4 days ago