InfoSecBulletin Cybersecurity for mankind
Outlook displays an alert when a user receives an email from an unfamiliar address. The alert message says “You don’t often get email from [email protected]. Learn why this is important”. Microsoft refers to this as the First Contact Safety Tip. It is one of the anti-phishing measures provided by Exchange Online Protection (EOP) and Microsoft Defender for organizations using Office 365.
You can change how the First Contact Safety Tip is displayed in an HTML email by using CSS style tags.
AI Finds Nation-State-Level Zoom Flaw in Under 24 Hours, Zero-Click Attack Exposed
Hacker Actively Exploit SonicWall and SharePoint Flaws
Gunra Ransomware Leverage Fortinet VPN Flaws to Evade MFA Obtaining Enterprise Data
Hackers accessed a US defense manufacturer’s Microsoft 365 account via phishing.
Google Play Apps Utilize Stealth Loaders to Spread Anatsa Banking Malware
Bangladeshi org listed “the Gentlemen’ ransomware victim list: CIRT warns
Around 800 Malicious npm Packages Distribute Cross-Platform RAT and Infostealer
Google Chrome 151 Update Fixes 41 Flaws, 6 Critical
Swiss gov.t SharePoint incident compromised 200 accounts
Azad president, Secretary Post Heads to Contest: ISACA Dhaka Chapter Election
To hide the First Contact Safety Tip in an HTML email, we can change the background and font colors to white. This will make the alert effectively invisible to the end user.
<head>
</head>
<head>
<style>
a {
display: none;
}
td div {
color: white;
font-size: 0px;
}
table tbody tr td {
background-color: white !important;
color: white !important;
}
</style>
</head>
…[SNIP]…
By using this HTML code in an e-mail, the alert does not show up in the email body anymore!
Note that the e-mail preview (highlighted in red) still begins with the Safety Tip.
Responsible Disclosure:
After developing a proof of concept, and preparing an advisory, we made Microsoft aware of these issues through the Microsoft Researcher Portal (MSRC). Microsoft chose to not address this behavior for now: (Click here to read the full report)
