How to Check Suspicious Email Attachments & Analyze its Content

In today’s world, any investigator must know how to check suspicious email attachments at their fingertips. These files that accompany an email message are the most common attack vectors through which nefarious entities perform their dirty deeds.

Moreover, if users open an attachment that is suspicious and don’t follow the proper protocol, they can unknowingly invite malware, ransomware, and other malicious software onto their devices and network. As these programs are designed to spread they can can lead to significant financial losses and reputational damage.

So we prepared this guide with the sole aim of making you better at identifying the red flags present in a would-be fake email attachment. Let us start by defining what exactly makes an attachment malicious in nature. 

What are Suspicious Attachments?

Attachments that arrive in an inbox fall into suspicion when their source is not known. As these are the types of files that raise the most concern at the receiver end. What makes them dangerous is the fact that behind seemingly harmless-looking, documents, PDFs hide malware, viruses, or bots. They hijack your email account, infiltrate your system, and steal personal information.

Likeliness of a attachment being termed suspicious has a lot to do with the file type it belongs to. The most well-known culprits include executable files like .exe or .app. Sometimes these files are not directly present but instead a compressed copy in the form of .zip or .rar format. This is mostly due to the email size limit imposed by the providers. 

Moreover, there have been instances where Microsoft Office files like .docx or .xls were used as carrier agents to deploy dangerous macros like in the infamous case in 2015 where the notorious Sandworm team infiltrated the Ukranian Electric power system with help of similar agents.

So now that we know what a suspicious attachment is the next logical question is how to identify it.

Identify Suspicious Attachments in Email

Emails that contain an attachment that is sent with the wrong intent have all sorts of characteristics. However, keep in mind no single symptom is enough to put an attachment under suspicion so make the decision to flag it only after a thorough investigation.

Check if you or the people you know are the only ones on the receiver list. Professional emails, no matter how urgent don’t appear out of nowhere. There is always a backgroundd and context behind a message. If the message is confusing, written in a mneer that doest resemble the person than it might raise a few eyebrows. If the sender is genuine but the message then it might indicate that there is an insider who is misusing their company credentials or the id is hacked. 

A spoofed email address makes it more difficult to be 100% sure. So another important thing to watch out for is whether your email address is in the “To” section or not. If the latter is the case then 

Many times due to the length of the message, attachment details are hidden. Only the first few characters are visible rest of the content hides behind the continuation … part. 

No worries there is a trick to get the full attachment info just take your cursor over the attachment. A small bubble with appear that contains the full attachment name along with its file type. Use it to your advantage in figuring out if this is an attachment you would open or not.

But not just the attachment but the email message itself may be suspicious. 

Remember do not click an attachment under any circumstance. Not unless you have ensured that it is safe to do so, or have gotten a green light from the security team.

What to Do if You Open a Suspicious Attachment?

If a user accidentally opens a harmful attachment it can be a quite nerve-wracking experience.

So if you are someone who has accidentally found yourself with an already opened suspicious attachment do the following to protect your system and data:

Sever the Internet connection: Although malware/viruses and other entities are designed to work offline. During the early stages of cyber infection, they communicate with the souce and inform them of the successful deployment. They then receive the next set of instructions. So if you disconnect the affected device you prevent any of this communication from happening. Therefore turn off wifi router and put your device on aeroplane mode ASAP.

Start a Antivirus Scan: Use your system installed antivirus program to conduct a full scan of your system. Don’t rely on the quick scan in this emergency situation. Most of the paid anti virus softwares can detect hand instruct you on what to do incase a malicious files or activity is found in your machine. To make sure you are not caught off guard keep your antivirus upto date at all times. This is because there is always a new form of virus which older versions may not be able to recognize.

Drag and drop it in the junk folder or right-click and delete.

Do any one of these and it will ensure that this particular email along with it no longer appears inside your inbox. Moreover, after a preset time (30 Days). This will be permanently removed on its own, if you believe that this was a mistake or want to perform hard deletion of suspicious mali manually go to the junk/delete folder/bin on the email platform you are using and perform the required steps.

Best Practices to Check Suspicious Attachments

An informed workspace environment is the best prevention tactic for any organization. So hold regular webinars, and knowledge sessions, and keep the staff up to date with the latest email attachment attacks.

To ensure that your data remains accessible after you check suspicious email attachments you need keep a secure backup of all email conversations. Build a separate isolated and if possible offline environment. Also, make sure that you schedule the backup regularly.

Only open attachments from the people you expect at the time you expect. 

Keep an eye on the messaging look for red flags and make a logical decision instead of an emotional one. Don’t register your email addresses on shady websites, use temporary mail or other online tools instead.

Professional Means of Suspicious Attachment Detection

MailXaminer is the one true utility that can perform this job in the most simple manner. This email forensics tool contains all sorts of media filters to identify and segregate email attachments on the type of correctly. 

You can use a variety of search options to filter out the common terminology used in emails and apply the OCR filter to reveal the text information inside image attachments. 

The tool can digest attachments while it’s processing the mail content. There you can put in the suspicious zip files, PDFs, and other data found as attachments. With over 80+ acceptable source types the tool is ready for any scenario to assist you in your digital investigation of suspicious email attachments.

Conclusion

Now you are well versed on how to check suspicious email attachments in any form and also aware on the procedure to deal with a fake email attachment. By understanding the risks involved and taking all the safety precautions no malicious attachment will ever harm your system. Moreover, forensics analysts can do an in-depth analysis on patterns used by the attackers and of the attachments themselves with the email forensic utility we mentioned earlier.