Microsoft 365 - List/Newsletter Web Form Attacks and How to Protect your Microsoft 365 Account

This document explains how to protect your UW-Madison Office 365 account from email list and newsletter web form attacks. These types of attacks target user email accounts by flooding their Inboxes with web form messages (e.g. "sign-up confirmation", "response received") and are a type of denial of service attack. See below for steps to take to protect your individual Office 365 account.

First, be vigilant for other malicious activity in your email or with your NetID account. List bomb attacks are sometimes used to mask other activity. For example you might be so busy dealing with the flood of email that you don't notice an account change notification.

Next, do not use the Report Suspicious Outlook add-in to submit the newsletter and web signup as suspicious. The Report Suspicious processing explores links in the submitted messages and may result in confirmation that you want to receive further communications from the website.

Finally, you may be able to mitigate the attack by creating an inbox rule to filter the messages to a separate folder or delete them entirely.

  1. Create an Inbox rule in Outlook on the web with the following settings:

    • Message header includes: List-Unsubscribe, List-Id:, LIST_HEADER

    • Move to: a folder of your choice for further review or deletion.

    • Recipient address includes: feel free to include campus address domains and in your exceptions so that WiscList and Google Groups messages don't get diverted by this Inbox rule. Add any other domains or specific email addresses you don't want affected by the rule, as well.
    • Outlook on the web settings page, creating a new rule, with settings described in this document.

  2. Click Save

Keywordsmicrosoft ms office365 o365 m365 microsoft 365 dos denial of service emails inbox rules message filters folder spam web owa newsletter web junk mail bomb mailbomb lists bomb listbomb   Doc ID102875
OwnerO365 S.GroupMicrosoft 365
Created2020-06-08 11:53:55Updated2024-03-16 16:50:42
SitesDoIT Help Desk, Microsoft 365
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