Why are email attachments potentially dangerous

Some users have been reported that they receive the ‘Outlook blocked access to the following potentially unsafe attachments’ error at the top of the Reading Pane. Most users report that the issue is occurring whenever they try to open an email that contains an attachment. Outlook blocked access to the following potentially unsafe attachments What causes the ‘Outlook blocked access to the following potentially unsafe attachments’ error? We investigated this particular issue by looking at various user reports and the repair strategies that they used to to get the issue resolved. From what we gathered, there are several common scenarios that are known to trigger this particular error message: • The attachment was blocked because it contains an extra ‘.'(dot) at the end of the filename– Outlook will no longer accept attachments that don’t follow the official attachment guidelines. This security update was introduced to patch a vulnerability that could allow remote code execution. • Outlook is updated with the security update that blocks certain attachments– Security updates • The attachment is of an unsupported extension– There’s a whole list of unsupported extensions that Outlook no longer agrees with. Here’s a Although Outlook blocks certain attachments for security reasons, it also ends up affecting a lot of users that don’t have shady reasons. For example, if you’re a programmer and you receive a .js file through Outlook, you will no longer be able to open it if you have t...

By Eric Howes, KnowBe4's Principal Lab Researcher Over the past six to nine months .DOC and .JS file attachments have dominated the news surrounding the rise in Although not nearly as prevalent as .JS and .DOC file attachments, .HTML attachments are common enough -- and dangerous enough -- that we decided to review how the bad guys present these attachments to unsuspecting users and trick them into coughing up data that could be used to exploit your organization. Note that these phishing emails are reported to us through the , which means they were missed by all existing security layers. All the example HTML attachments discussed below were seen within the past three weeks. Why Use .HTML Attachments? So far as we can tell, .HTML attachments have two mainadvantages that the bad guys exploit when using them in phishing attacks: 1. Reduced chance of AV detection Carefully crafted .HTML files can reduce the chances that phishing emails sporting those attachments will be stopped by email security software or devices. While .EXE and Office files (.DOC, .XLS, etc.) pose obvious threats in a Windows environment and have a long history of being used in malspam (malicious spam email), .HTML files are not commonly associated with email-borne attacks -- at least not recently ( 2. User familiarity Although your users and employees may not recognize the potential threat of .HTML attachments, that doesn't necessarily mean they aren't familiar with them. HTML attachments are commonly used...

$ United States dollar € Euro R$ Brazilian real £ British pound AED UAE dirham ARS Argentine peso AU$ Australian dollar BGN Bulgarian lev CA$ Canadian dollar CHF Swiss franc CLP Chilean peso CN¥ Chinese yuan COP Colombian peso CZK Czech koruna DKK Danish krone EGP Egyptian pound HK$ Hong Kong dollar HUF Hungarian forint IDR Indonesian rupiah ₪ Israeli new shekel INR Indian rupee ¥ Japanese yen ₩ South Korean won MX$ Mexican peso MYR Malaysian ringgit NOK Norwegian krone NZ$ New Zealand dollar PLN Polish złoty RON Romanian leu RUB Russian ruble SAR Saudi riyal SEK Swedish krona SGD Singapore dollar ฿ Thai baht TRY Turkish lira NT$ New Taiwan dollar UAH Ukrainian hryvnia ₫ Vietnamese Dong ZAR South African rand Short on time? Click on one of the links below to skip straight to the troubleshooting steps: • • However, if you want to know a bit more about why Gmail flags some emails (and not others), then keep reading. Why Do I See “This Message Seems Dangerous”? The short answer is that it’s impossible to know exactly why Gmail flags some emails with this banner. However, here are a few potential reasons: • Too many recipients (you’ll often see this banner appear on chain emails). • Bad grammar/punctuation. • Too many attachments. • Too many images. • Too many hyperlinks. • The sender is already in a database of suspicious email addresses. • The sender doesn’t have email authentication set up. • The email hasn’t got an unsubscribe button (or link) and is coming from a business...

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Note Jump to the remediation article Before you begin Make sure that the following requirements are met: • Your organization has • • Your organization has policies defined for anti-spam, anti-malware, anti-phishing, and so on. See • You are a global administrator, or you have either the Security Administrator or the Search and Purge role assigned in the Microsoft 365 Defender portal. For more information, see Preview role permissions To perform certain actions, such as viewing message headers or downloading email message content, you must have the Preview role added to another appropriate role group. The following table clarifies required roles and permissions. Activity Role group Preview role needed? Use Threat Explorer (and Real-time detections) to analyze threats Global Administrator Security Administrator Security Reader No Use Threat Explorer (and Real-time detections) to view headers for email messages as well as preview and download quarantined email messages Global Administrator Security Administrator Security Reader No Use Threat Explorer to view headers, preview email (only in the email entity page) and download email messages delivered to mailboxes Global Administrator Security Administrator Security Reader Preview Yes Note Preview is a role, not a role group. The Preview role must be added to an existing role group or a new role group in the Microsoft 365 Defender portal. For more information, see The Global Administrator role is assigned the Microsoft 365 admi...

Gmail may sometimes display a red warning banner when you receive an email from suspicious senders. The banner usually reads as follows: This message seems dangerous. Many people marked similar messages as phishing scams, so this might contain unsafe content. Avoid clicking links, downloading attachments, or replying with personal information. This warning may also appear when you send emails using genuine apps, services, or domain accounts. For example, this issue is quite common among people who use SaasS services or monitoring apps. What To Do If Gmail Says This Message Seems Dangerous ⇒ Note: Always take security alerts seriously. If Gmail says an email is dangerous, start from the assumption that’s true. If the alert is a false-positive, nothing happens. But if the alert is real and you ignore it, you risk getting your computer infected with malware and your data stolen by hackers. Click on Looks Safe Use this option only if you’re completely sure the sender is a genuine person or service and they’re not trying to spam you, spread malware or steal your data. Don’t click the “ Looks Safe” button if the email is coming from an unknown sender. Also, make sure there are no disguised links in the email. In this manner, Gmail’s bots will gradually learn that those emails are safe and should not be flagged as suspicious. Additionally, you can also add the sender to your Contacts list. Declutter Your Emails If the messages you sent are labeled as dangerous, you need to declut...

Never open attachment from suspicious email Everyone who has e-mail addresses experiences unexpected messages sooner or later. Usually these spam emails are just newsletters or some other form of unwanted advertisement, but not every spam is harmless. Numerous phishing campaigns are distributed via email, and same goes for viruses, trojans and in recent years ransomware. You should always take extra attention when dealing with suspicious e-mails from unknown senders and especially if they contain attachment that supposedly contains something you need to see. Do not rely on spam filters, a lot of harmful emails may actually pass filters, that is until enough people flag them as spam. This article covers some of the basics about potential dangers of email attachment and be aware of the latest computer threats that may compromise your computer, or even mobile device. Why are unknown email attachments potentially dangerous? The answer to this question is actually quite simple, because they can easily be something else, for example viruses or malware that will infect your computer when you open the attachments. What may seem as a .pdf document or .jpg picture, can easily be JavaScript file with it's suffix renamed. In this scenario, when you open the attachment, the script will launch and do its infernal work in your computer. A simple click may ruin your whole computer and your data. Locky ransomware email spam The above picture is a spam email that distributes Locky ransomwar...

Were you about to open an attachment on your Outlook, but you’re unable to access them? Are you getting a message that the attachments are potentially unsafe? If this is happening to you, there are a few reasons for this issue. Outlook has a security feature that can block access to some attachments if it believes there are potential viruses attached. When you lose access to an attachment, you can’t open or make any changes to it. Luckily, there are a few ways to work around this issue and reclaim access to your attachments. So, let’s quickly learn how to do it. How to Fix Outlook Blocked Access Unsafe Attachments? Before we look at the solutions, we recommend restarting your Outlook first. Doing so will give a second chance to Outlook to re-check the attachment. In some cases, this can help prevent Outlook from locking it down. However, if it’s still not working, we can now apply other effective fixes: Rename the Attachment’s Extension Sometimes, Outlook can determine an attachment as a threat due to its extension only. In such a case, inform the sender to rename the file with a different extension. And once you have received the modified attachment, follow the steps below. 1. Right-click on the attachment and Copy it. 2. Save it on your computer and right-click on it again. 3. Select the option to rename. 4. Change the extension name to the original one then you can open it. Change Attachment Security Behavior In this step, we’re going to change settings in the Registry ...

Note Jump to the remediation article Before you begin Make sure that the following requirements are met: • Your organization has • • Your organization has policies defined for anti-spam, anti-malware, anti-phishing, and so on. See • You are a global administrator, or you have either the Security Administrator or the Search and Purge role assigned in the Microsoft 365 Defender portal. For more information, see Preview role permissions To perform certain actions, such as viewing message headers or downloading email message content, you must have the Preview role added to another appropriate role group. The following table clarifies required roles and permissions. Activity Role group Preview role needed? Use Threat Explorer (and Real-time detections) to analyze threats Global Administrator Security Administrator Security Reader No Use Threat Explorer (and Real-time detections) to view headers for email messages as well as preview and download quarantined email messages Global Administrator Security Administrator Security Reader No Use Threat Explorer to view headers, preview email (only in the email entity page) and download email messages delivered to mailboxes Global Administrator Security Administrator Security Reader Preview Yes Note Preview is a role, not a role group. The Preview role must be added to an existing role group or a new role group in the Microsoft 365 Defender portal. For more information, see The Global Administrator role is assigned the Microsoft 365 admi...

Gmail may sometimes display a red warning banner when you receive an email from suspicious senders. The banner usually reads as follows: This message seems dangerous. Many people marked similar messages as phishing scams, so this might contain unsafe content. Avoid clicking links, downloading attachments, or replying with personal information. This warning may also appear when you send emails using genuine apps, services, or domain accounts. For example, this issue is quite common among people who use SaasS services or monitoring apps. What To Do If Gmail Says This Message Seems Dangerous ⇒ Note: Always take security alerts seriously. If Gmail says an email is dangerous, start from the assumption that’s true. If the alert is a false-positive, nothing happens. But if the alert is real and you ignore it, you risk getting your computer infected with malware and your data stolen by hackers. Click on Looks Safe Use this option only if you’re completely sure the sender is a genuine person or service and they’re not trying to spam you, spread malware or steal your data. Don’t click the “ Looks Safe” button if the email is coming from an unknown sender. Also, make sure there are no disguised links in the email. In this manner, Gmail’s bots will gradually learn that those emails are safe and should not be flagged as suspicious. Additionally, you can also add the sender to your Contacts list. Declutter Your Emails If the messages you sent are labeled as dangerous, you need to declut...