Microsoft Visual Basic, Excel Scripting, & Their Cybersecurity Implications: An In-Depth Discussion

Microsoft Visual Basic (VB) and Excel scripting are potent tools for automating tasks and customizing applications. However, malicious actors can also exploit their capabilities, presenting significant cybersecurity risks.

A recent article by Sergiu Gatlan announced that more changes are coming to VB following changes already announced for Excel. In the world of cyber exploits, both tools Microsoft works to eliminate are used by adversaries daily. In this blog, we will look at what both are, how they are being exploited, and finally, why it is so important to fix these.

Microsoft Visual Basic: An Overview

Microsoft Visual Basic, often referred to as VB or VBA (Visual Basic for Applications), is a programming language developed by Microsoft. It is designed to be an easy-to-learn and flexible language for building Windows applications, automating repetitive tasks, and customizing software. Some of the key features of Microsoft Visual Basic include:

• Simplicity: VB is known for its clarity and readability. It uses a straightforward syntax, making it accessible to beginners and experienced developers.

• Automation: VB is widely used for automating tasks and processes in various Microsoft applications, including Excel, Word, Access, and Outlook.

• Customization: The customization feature allows users to create custom functions and macros, tailoring software to specific needs.

• Integration: VB can seamlessly integrate with other Microsoft technologies, facilitating interaction with databases, web services, and external applications.

Excel Scripting: A Practical Application of VB

Excel scripting is the automation of tasks within Microsoft Excel using Visual Basic for Applications (VBA). Excel is a spreadsheet program for data analysis, reporting, and calculations. With Excel scripting, users can automate repetitive tasks, create custom functions, and design user interfaces within Excel. Excel Scripting works by:

• Recording Macros: Excel provides a feature for recording macros, essentially scripts that automate a series of actions performed in Excel. Users can record these actions, and Excel will generate VBA code replicating the steps.

• VBA Editor: Excel has a built-in VBA editor, allowing users to write, modify, and run VBA code. This editor provides a robust environment for custom scripts tailored to specific needs.

• Integration with Excel Objects: Excel scripting works by manipulating Excel objects, such as workbooks, worksheets, cells, and charts. Users can write code to interact with these objects, perform calculations, and automate data processing.

• User Forms: VBA in Excel also allows the creation of user forms. These custom dialog boxes enhance user interaction with spreadsheets, making data entry and retrieval more efficient.

The Cybersecurity Dangers of Microsoft Visual Basic and Excel Scripting

While Microsoft Visual Basic and Excel scripting are valuable tools for enhancing productivity, they can pose significant cybersecurity threats when used maliciously. Here are some of the critical dangers to consider:

• Macro Malware: One of the most prominent cybersecurity concerns associated with Excel scripting is the potential for macro malware. Malicious actors can embed harmful VBA macros within seemingly harmless Excel files. When a user opens such a file, the macro runs automatically, executing negative actions like spreading malware, stealing data, or compromising the host system.

• Phishing Attacks: Excel scripting can be used to craft convincing phishing attacks. Malicious actors send Excel files or documents with embedded scripts, prompting users to enable macros, often under the pretext of accessing critical information or unlocking content. When macros are enabled, the malicious code is executed, compromising the system and potentially exfiltrating sensitive data.

• Data Exfiltration: when used maliciously, Excel scripting can be employed for data exfiltration. An attacker can create a VBA script that extracts sensitive information from Excel spreadsheets and sends it to a remote server. This data theft can include confidential business data, financial records, or personal information.

• Ransomware Distribution: Malicious macros within Excel files can serve as a vector for distributing ransomware. When a user opens an infected Excel file, the ransomware payload can be unleashed, encrypting files and demanding a ransom for decryption.

• Zero-Day Exploits: Microsoft Visual Basic and Excel scripting vulnerabilities can be exploited to execute zero-day attacks. Cybercriminals can identify unpatched vulnerabilities in the software, creating custom scripts to target those weaknesses before security patches are available.

Mitigating the Cybersecurity Risks:

To mitigate the cybersecurity risks associated with Microsoft Visual Basic and Excel scripting, organizations and individuals should consider the following measures:

• User Education: Educating users about the dangers of enabling macros in Excel files from untrusted sources is crucial. They should be cautious and verify the authenticity of documents before enabling macros on a computer.

• Macro Security Settings: Configure macro security settings in Microsoft Office applications to disable macros by default. Users should only enable macros in documents from trusted sources.

• Regular Software Updates: Keep Microsoft Office and other software up to date to ensure that security patches are applied promptly. This reduces the risk of falling victim to known vulnerabilities.

• Antivirus and Antimalware Solutions: Employ robust antivirus and antimalware solutions to detect and block macro-based malware and phishing attempts.

• Network Segmentation: Implement network segmentation to contain the spread of malware in case of a successful breach. This reduces the attacker's ability to move laterally within the network.

• Email Filtering: Utilize email filtering solutions that can detect and block phishing emails containing malicious Excel files.

• Incident Response Plan: Develop a well-defined incident response plan that outlines procedures for detecting, containing, and remediating security incidents involving malicious scripts.

Conclusion

While VB and Excel scripting have been valuable tools for enhancing productivity and automating tasks, these tools also present cybersecurity risks, primarily in the form of macro malware, phishing attacks, data exfiltration, and potential ransomware distribution.

While Microsoft works to provide better options and control the risks, organizations must be vigilant and keep software updated, employ security solutions, implement network segmentation, and move to Zero Trust. By taking these measures, the potential cybersecurity threats associated with Microsoft Visual Basic and Excel scripting can be significantly reduced, ensuring these powerful tools' safe and secure use.