Microsoft's products are used almost everywhere, but sometimes even the biggest tech giants slip up. In May 2024, the cybersecurity world buzzed about a new Bing search vulnerability: CVE-2024-30041. It allowed attackers to spoof Bing search results, putting millions of users at phishing or misinformation risk. In this long read, we'll go through — in simple language — what CVE-2024-30041 is, show some code, and explain exactly what was going on behind the scenes.

What is CVE-2024-30041?

CVE-2024-30041 is a search spoofing vulnerability in Microsoft's Bing search engine. An attacker could manipulate what the victim sees in the Bing search results by misusing how Bing handles certain web requests. In practical terms, this means a hacker could make Bing show links or advertisements chosen by the attacker, fooling users into clicking malicious or scammy sites.

Reference:
- Microsoft Security Update Guide | CVE-2024-30041
- Huntress Security blog: Bing Spoofing Vulnerability

How Did the Vulnerability Work?

Every time you search on Bing (or any search engine), your browser sends requests to Microsoft's servers, and they reply with a list of search results. But with this vulnerability, an attacker could craft a special link that, when opened, made Bing show whatever results the attacker wanted.

This could be achieved by abusing an unsecured query parameter within Bing's search request and response process.

Suppose Bing accepted input like this (simplified for illustration)

https://www.bing.com/search?q=YOURSEARCH&customResults=PARAMETER

The bug: Bing was not properly validating or sanitizing the customResults parameter. An attacker could send a specially-crafted string as customResults that inserted HTML or JavaScript or directly replaced sections in the response.

Step-by-Step Attack

1. Craft a spoofed URL: The attacker crafts a URL with their own search results or ads embedded in the vulnerable parameter.

2. Send link to victim: The attacker sends the spoofed search link via email, social media, or even through ads.

3. Victim clicks link: The victim lands on Bing. Instead of genuine search results, the page shows malicious or misleading results controlled by the attacker.

4. Phishing/Scam: If the victim clicks these links, they could end up on a phishing site, download malware, or be exposed to scams.

Simple Code Example

Here’s a Python snippet to craft a fake Bing search link exploiting this vulnerability (educational use only!):

import urllib.parse

search_query = "Microsoft Bing"
spoofed_html = '''
<li class="b_algo">
    <h2><a href="https://malicious-site.com">Free Microsoft Gift Card</a></h2>
    <div class="b_caption">
        <p>Click here to claim your free card! Official deal.</p>
    </div>
</li>
'''
payload = urllib.parse.quote(spoofed_html)

bing_url = f"https://www.bing.com/search?q={urllib.parse.quote(search_query)}&customResults={payload}";
print("Spoofed Bing URL: " + bing_url)

If the bug was still live, opening this bing_url would make Bing show a fake "Free Microsoft Gift Card" result at the top!

Proof-of-Concept (PoC) – How a Real-World Exploit Looked

A real PoC (shared by Huntress researchers) used POST or GET requests with manipulated parameters. Attackers found that by sending raw HTML via a specific parameter, Bing would render their content on the search page.

Here’s what such a request might look like (in simplified form)

GET /search?q=apple&customResults=%3Cli%3ESPOOFED+RESULT%3C/li%3E HTTP/1.1
Host: www.bing.com

Ad Fraud: Intercept ad clicks and profit from them.

The attack was *invisible* to most users — everything looked like a normal Bing page.

Was this Fixed?

Yes. Microsoft released a patch quickly after receiving responsible disclosure reports. If you're using Bing, the fix is applied automatically — no action is necessary.

- Microsoft Security Advisory
- Huntress Labs technical writeup

Should I Worry?

If you keep your browser up-to-date and avoid clicking suspicious Bing search links, you’re safe. This bug is now history, but it’s a great reminder to always be careful about unexpected links, even if they look like they come from popular search engines.

Even world-class services like Bing can have vulnerabilities.

- Always treat search results (especially from "shared" search links) with a healthy dose of skepticism.

Final Thoughts

CVE-2024-30041 is a great case study in web vulnerability. It shows how an overlooked parameter can endanger millions. Stay sharp — and think twice before clicking unusual search links!


Further Reading:
- Microsoft CVE-2024-30041 Official Page
- Huntress Labs: The Bing Search Spoofing Bug
- OWASP Input Validation cheat sheet

Timeline

Published on: 05/14/2024 17:17:13 UTC
Last modified on: 06/19/2024 20:58:47 UTC