Malicious Excel Add-Ins Are Being Used As The Initial Intrusion Vector By APT Hackers.

Malicious Excel Add-Ins – APT hackers are using malicious Excel add-ins as an initial intrusion vector in one of their latest tactics. Nation-states often sponsor highly skilled and well-funded cyber criminals, known as Advanced Persistent Threat (APT) hackers, to carry out cyber attacks.

APT hackers design these add-ins to look legitimate and often masquerade them as legitimate software or tools that users might need for their work. However, once installed, these add-ins can give the APT hacker full control over the victim’s computer, allowing them to steal sensitive data, plant malware, or even use the victim’s computer as part of a botnet for future attacks.

So how do these malicious Excel add-ins work, and how can you protect yourself from falling victim to this tactic?

How Malicious Excel Add-ins Work

Users typically download Excel add-ins from the Internet and install them through the Excel Options menu. Users can install small software programs called Excel add-ins into Excel to provide additional functionality or features.

Hackers design malicious Excel add-ins that resemble legitimate software or tools and contain malicious code. Once the add-in is installed, it gives the hacker full control over the victim’s computer. The user designs legitimate Excel add-ins to provide additional functionality or features, but these add-ins differ from them

Malicious Add-in

One common method used by APT hackers is to send a phishing email to a target, with the email containing a link to download the malicious add-in. APT hackers often design the email to look like it is coming from a trusted source and contain a compelling message that entices the user to click on the link and download the malicious add-in. APT hackers specifically design the email to deceive the user and execute the malicious activity of installing the add-in.

Steal Sensitive Credentials

Once the user clicks on the link and downloads the add-in, it installs into Excel and begins executing its malicious code. This code may include instructions to steal sensitive data, such as login credentials or financial information, or it may include instructions to download and install additional malware onto the victim’s computer.

Some APT hackers will even go so far as to set up a fake website that looks like a legitimate software vendor, and they will use this website to distribute their malicious Excel add-ins.

Protecting Yourself from Malicious Excel Add-ins

So how can you protect yourself from falling victim to this tactic? Here are a few best practices to follow:

  1. Be wary of phishing emails: If you receive an email that looks suspicious or contains a link to download an Excel add-in, be cautious. Verify the authenticity of the email and the link before clicking on it.
  2. Use caution when downloading add-ins: Be sure to only download Excel add-ins from trusted sources. Do some research before downloading an add-in to ensure that it is legitimate.
  3. Enable macros security: Excel has a security feature that allows you to enable macros security, which will prompt you to enable or disable macros when you open a document that contains them. This can help prevent malicious macros from running without your knowledge.
  4. To help detect and remove any malicious software that may have been installed through a malicious Excel add-in, make sure to have up-to-date antivirus software installed on your computer.


APT hackers are constantly evolving their tactics, and the use of malicious Excel add-ins as an initial intrusion vector is a particularly clever and effective method. By following the best practices listed above, you can help protect yourself and your organization from falling victim to this tactic. Stay vigilant and be sure to regularly update your security

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