Avoid having your email account stolen via fake "Overdue Invoice" emails

Also Known As: "Overdue Invoice" phishing email
Damage level: Medium

What kind of email is "Overdue Invoice"?

After analyzing the "Overdue Invoice" email, we determined that it is spam. The letter urges the recipient to pay an overdue invoice and continue the positive working relationship with the sender. Details of the supposed invoice can be found in the attachment, which is a phishing file targeting email account log-in credentials.

Overdue Invoice email spam campaign

"Overdue Invoice" email scam overview

The scam email with the subject "Urgent: Settle Invoice to Prevent Legal Action" (may vary) is presented as a letter from a business partner. The sender expresses appreciation for the partnership shared with the recipient and brings to their attention an unpaid invoice.

The email lists the date that it had to be settled. Details of the invoice can be found in the attached file. The recipient is requested to process the payment as soon as possible, and if it is already underway – they are to disregard this missive.

It must be emphasized that all these claims are false, and this mail is in no way associated with any real individuals or entities.

After inspecting the attachment – "Overdue Invoice.shtml" – we learned that it is a phishing file. This file asks the user to confirm their details by signing into their email account – thus gaining access to the online PDF documents.

Phishing files record provided information and send it to cyber criminals. Victims of this scam risk losing their emails and potentially the accounts/platforms registered through them.

To elaborate on the possible misuse, scammers can steal the identities of social account owners (e.g., emails, social networking/media, messengers, etc.) and ask the contacts/friends/followers for loans or donations, promote scams, and even proliferate malware by sharing malicious files/links.

Furthermore, stolen finance-related accounts (e.g., online banking, money transferring, e-commerce, digital wallets, etc.) can be used to make fraudulent transactions and/or online purchases.

In summary, by trusting an email like "Overdue Invoice" – users may experience serious privacy issues, financial losses, and even identity theft.

If you have already disclosed your log-in credentials – immediately change the passwords of all potentially exposed accounts and inform their official support.

Threat Summary:
Name "Overdue Invoice" phishing email
Threat Type Phishing, Scam, Social Engineering, Fraud
Fake Claim Recipient is requested to pay an overdue invoice.
Attachment(s) Overdue Invoice.shtml (filename may vary)
Detection Names Avast (HTML:Phishing-CMG), Combo Cleaner (Trojan.Script.GenericKDZ.25051), ESET-NOD32 (HTML/Phishing.Agent.EIX), Kaspersky (Trojan.HTML.Agent.aca), Microsoft (Trojan:Script/Wacatac.B!ml), Full List Of Detections (VirusTotal)
Symptoms Unauthorized online purchases, changed online account passwords, identity theft, illegal access of the computer.
Distribution methods Deceptive emails, rogue online pop-up ads, search engine poisoning techniques, misspelled domains.
Damage Loss of sensitive private information, monetary loss, identity theft.
Malware Removal (Windows)

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Phishing spam campaign examples

"NEW DOCUMENT(S) FOR REVIEW ON CLOUD", "Central Bank Of Nigeria", and "Check Out These Messages!" are just a few examples of phishing emails we have inspected recently.

Various scams are promoted through spam mail, and it is even used to distribute malware (e.g., trojans, ransomware, cryptominers, etc.). These emails can be plain or elaborately disguised as messages from legitimate service providers, companies, institutions, organizations, authorities, and other entities.

Due to how prevalent spam mail is and how well-crafted it can be – we strongly recommend exercising caution with incoming emails, DMs/PMs, SMSes, and other messages.

How do spam campaigns infect computers?

Spam campaigns proliferate malware by distributing infectious files. They can be attached to or linked inside the emails/messages. Malicious files come in various formats, e.g., documents (PDF, Microsoft Office, Microsoft OneNote, etc.), archives (RAR, ZIP, etc.), executables (.exe, .run, etc.), JavaScript, and so on.

Infection chains are triggered when such files are opened. However, some formats might require additional actions to jumpstart malware download/installation processes. For example, Microsoft Office documents need users to enable macros commands (i.e., editing/content), while OneNote files require them to click on embedded files/links.

How to avoid installation of malware?

We advise treating incoming emails and other messages with care. Attachments or links present in dubious/irrelevant mail must not be opened, as they can be virulent. We recommend using post-2010 Microsoft Office versions since their "Protected View" mode prevents automatic macro command execution.

However, malware is not distributed exclusively via spam mail. Therefore, we also advise being vigilant while browsing, as fraudulent and malicious online content typically appears genuine and innocuous.

Furthermore, all downloads must be performed from official and verified channels. Another recommendation is to activate and update software by using legitimate functions/tools, as illegal activation tools ("cracks") and third-party updaters can contain malware.

We must stress the importance of having a dependable anti-virus installed and kept updated. Security programs must be used to run regular system scans and to remove detected threats. If you've already opened malicious attachments, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate infiltrated malware.

Text presented in the "Overdue Invoice" spam email letter:

Subject: Urgent: Settle Invoice to Prevent Legal Action

Hello -,

I trust this email finds you well. We appreciate your partnership and would like to bring to your attention an outstanding matter regarding an overdue invoice, with a due date of September 1, 2023.


As of today, the invoice remains unpaid, and it is now overdue. We kindly request your immediate attention to this matter to ensure that your account remains in good standing.

Attached to this email is a copy of the invoice for your reference. Please review the attached document and process the payment as soon as possible.

For your convenience, our preferred payment methods and bank details are included in the invoice. If you have already initiated the payment, kindly disregard this reminder.

We value your business and would like to maintain our positive working relationship. Your prompt attention to this matter is greatly appreciated.

Margit Backmann
Comercial-C. M. B. Srl
Via Medini, 14
44122 Ferrara (FE)
Tel / Fax: 0532.64482
Mobile 333.1352073

Screenshot of the phishing file attached to this spam email ("Overdue Invoice.shtml"):

Overdue Invoice scam email attachment (Overdue Invoice.shtml)

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Quick menu:

Types of malicious emails:

Phishing email icon Phishing Emails

Most commonly, cybercriminals use deceptive emails to trick Internet users into giving away their sensitive private information, for example, login information for various online services, email accounts, or online banking information.

Such attacks are called phishing. In a phishing attack, cybercriminals usually send an email message with some popular service logo (for example, Microsoft, DHL, Amazon, Netflix), create urgency (wrong shipping address, expired password, etc.), and place a link which they hope their potential victims will click on.

After clicking the link presented in such email message, victims are redirected to a fake website that looks identical or extremely similar to the original one. Victims are then asked to enter their password, credit card details, or some other information that gets stolen by cybercriminals.

Email-virus icon Emails with Malicious Attachments

Another popular attack vector is email spam with malicious attachments that infect users' computers with malware. Malicious attachments usually carry trojans that are capable of stealing passwords, banking information, and other sensitive information.

In such attacks, cybercriminals' main goal is to trick their potential victims into opening an infected email attachment. To achieve this goal, email messages usually talk about recently received invoices, faxes, or voice messages.

If a potential victim falls for the lure and opens the attachment, their computers get infected, and cybercriminals can collect a lot of sensitive information.

While it's a more complicated method to steal personal information (spam filters and antivirus programs usually detect such attempts), if successful, cybercriminals can get a much wider array of data and can collect information for a long period of time.

Sextortion email icon Sextortion Emails

This is a type of phishing. In this case, users receive an email claiming that a cybercriminal could access the webcam of the potential victim and has a video recording of one's masturbation.

To get rid of the video, victims are asked to pay a ransom (usually using Bitcoin or another cryptocurrency). Nevertheless, all of these claims are false - users who receive such emails should ignore and delete them.

How to spot a malicious email?

While cyber criminals try to make their lure emails look trustworthy, here are some things that you should look for when trying to spot a phishing email:

  • Check the sender's ("from") email address: Hover your mouse over the "from" address and check if it's legitimate. For example, if you received an email from Microsoft, be sure to check if the email address is @microsoft.com and not something suspicious like @m1crosoft.com, @microsfot.com, @account-security-noreply.com, etc.
  • Check for generic greetings: If the greeting in the email is "Dear user", "Dear @youremail.com", "Dear valued customer", this should raise suspiciousness. Most commonly, companies call you by your name. Lack of this information could signal a phishing attempt.
  • Check the links in the email: Hover your mouse over the link presented in the email, if the link that appears seems suspicious, don't click it. For example, if you received an email from Microsoft and the link in the email shows that it will go to firebasestorage.googleapis.com/v0... you shouldn't trust it. It's best not to click any links in the emails but to visit the company website that sent you the email in the first place.
  • Don't blindly trust email attachments: Most commonly, legitimate companies will ask you to log in to their website and to view any documents there; if you received an email with an attachment, it's a good idea to scan it with an antivirus application. Infected email attachments are a common attack vector used by cybercriminals.

To minimise the risk of opening phishing and malicious emails we recommend using Combo Cleaner Antivirus for Windows

Example of a spam email:

Example of an email spam

What to do if you fell for an email scam?

  • If you clicked on a link in a phishing email and entered your password - be sure to change your password as soon as possible. Usually, cybercriminals collect stolen credentials and then sell them to other groups that use them for malicious purposes. If you change your password in a timely manner, there's a chance that criminals won't have enough time to do any damage.
  • If you entered your credit card information - contact your bank as soon as possible and explain the situation. There's a good chance that you will need to cancel your compromised credit card and get a new one.
  • If you see any signs of identity theft - you should immediately contact the Federal Trade Commission. This institution will collect information about your situation and create a personal recovery plan.
  • If you opened a malicious attachment - your computer is probably infected, you should scan it with a reputable antivirus application. For this purpose, we recommend using Combo Cleaner Antivirus for Windows.
  • Help other Internet users - report phishing emails to Anti-Phishing Working Group, FBI’s Internet Crime Complaint Center, National Fraud Information Center and U.S. Department of Justice.

Frequently Asked Questions (FAQ)

Why did I receive this email?

Spam emails are not personal. They are distributed in large-scale operations – hence, thousands of users receive identical messages.

I have provided my personal information when tricked by this spam email, what should I do?

If you have provided your account credentials – immediately change the passwords of all possibly compromised accounts and inform their official support. And if the disclosed data was of a different personal nature (e.g., ID card details, passport photos/scans, credit card numbers, etc.) – contact the corresponding authorities without delay.

I have read a spam email but didn't open the attachment, is my computer infected?

Systems are infected when malicious attachments/links are opened; merely reading an email will not initiate these processes.

I have downloaded and opened a file attached to a spam email, is my computer infected?

Whether your device was infected might depend on the opened file's format. If it was an executable (.exe, .run, etc.) – most likely, yes. However, you might have avoided the infection if it was a document (.doc, .xls, .one, .pdf, etc.). These formats may require extra actions to initiate malware download/installation chains (e.g., enabling macro commands, clicking embedded files/links, etc.).

Will Combo Cleaner remove malware infections present in email attachments?

Yes, Combo Cleaner is designed to scan computers and remove detected threats. It is capable of detecting and eliminating most of the known malware infections. Keep in mind that since high-end malicious software usually hides deep within systems – performing a full system scan is paramount.

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About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

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