App Sec

• Viewing Page Source:

  • Viewing the page source can often give us clues into whether a framework is in use and, if so, which framework and even what version. Knowing the framework and version can be a powerful find as there may be public vulnerabilities in the framework, and the website might not be using the most up to date version. At
• Developer Tools - Debugger

  • This panel in the developer tools is intended for debugging JavaScript, and again is an excellent feature for web developers wanting to work out why something might not be working. But as penetration testers, it gives us the option of digging deep into the JavaScript code. In Firefox and Safari, this feature is called Debugger, but in Google Chrome, it's called Sources.
• Developer Tools - Network

  • The network tab on the developer tools can be used to keep track of every external request a webpage makes. If you click on the Network tab and then refresh the page, you'll see all the files the page is requesting. 
• AJAX:

  • With the network tab open, try filling in the contact form and pressing the Send Message button. You'll notice an event in the network tab, and this is the form being submitted in the background using a method called AJAX. AJAX is a method for sending and receiving network data in a web application background without interfering by changing the current web page.
• Content Discovery:

  • Content can be many things, a file, video, picture, backup, a website feature. When we talk about content discovery, we're not talking about the obvious things we can see on a website; it's the things that aren't immediately presented to us and that weren't always intended for public access. This content could be, for example, pages or portals intended for staff usage, older versions of the website, backup files, configuration files, administration panels, etc.
• Sitemap.xml

  • Unlike the robots.txt file, which restricts what search engine crawlers can look at, the sitemap.xml file gives a list of every file the website owner wishes to be listed on a search engine. These can sometimes contain areas of the website that are a bit more difficult to navigate to or even list some old webpages that the current site no longer uses but are still working behind the scenes.
• HTTP Headers

  • When we make requests to the web server, the server returns various HTTP headers. These headers can sometimes contain useful information such as the webserver software and possibly the programming/scripting language in use. In the below example, we can see the webserver is NGINX version 1.18.0 and runs PHP version 7.4.3. Using this information, we could find vulnerable versions of software being used. Try running the below curl command against the web server, where the -v switch enables verbose mode, which will output the headers

  
• Framework Stack

  • Once you've established the framework of a website, either from the above favicon example or by looking for clues in the page source such as comments, copyright notices or credits, you can then locate the framework's website. From there, we can learn more about the software and other information, possibly leading to more content we can discover.
• Google Hacking / Dorking

  • Google hacking / Dorking utilizes Google's advanced search engine features, which allow you to pick out custom content. You can, for instance, pick out results from a certain domain name using the site: filter, for example (site:tryhackme.com) you can then match this up with certain search terms, say, for example, the word admin (site:tryhackme.com admin) this then would only return results from the tryhackme.com website which contain the word admin in its content.

  
• Wappalyzer

  • Wappalyzer (https://www.wappalyzer.com/) is an online tool and browser extension that helps identify what technologies a website uses, such as frameworks, Content Management Systems (CMS), payment processors and much more, and it can even find version numbers as well.
• Wayback Machine

  • The Wayback Machine (https://archive.org/web/) is a historical archive of websites that dates back to the late 90s. You can search a domain name, and it will show you all the times the service scraped the web page and saved the contents. This service can help uncover old pages that may still be active on the current website.
• GitHub

  • To understand GitHub, you first need to understand Git. Git is a version control system that tracks changes to files in a project. Working in a team is easier because you can see what each team member is editing and what changes they made to files. When users have finished making their changes, they commit them with a message and then push them back to a central location (repository) for the other users to then pull those changes to their local machines.
• GitHub

  • Repositories can either be set to public or private and have various access controls. You can use GitHub's search feature to look for company names or website names to try and locate repositories belonging to your target. Once discovered, you may have access to source code, passwords or other content that you hadn't yet found
• S3 Buckets

  • S3 Buckets are a storage service provided by Amazon AWS, allowing people to save files and even static website content in the cloud accessible over HTTP and HTTPS. The owner of the files can set access permissions to either make files public, private and even writable. Sometimes these access permissions are incorrectly set and inadvertently allow access to files that shouldn't be available to the public. The format of the S3 buckets is http(s)://{name}.s3.amazonaws.com where {name} is decided by the owner
• What is Automated Discovery?

  • Automated discovery is the process of using tools to discover content rather than doing it manually. This process is automated as it usually contains hundreds, thousands or even millions of requests to a web server. These requests check whether a file or directory exists on a website, giving us access to resources we didn't previously know existed. This process is made possible by using a resource called wordlists.
• What are wordlists?

  • Wordlists are just text files that contain a long list of commonly used words; they can cover many different use cases. For example, a password wordlist would include the most frequently used passwords, whereas we're looking for content in our case, so we'd require a list containing the most commonly used directory and file names.
• Automation Tools

  • Although there are many different content discovery tools available, all with their features and flaws, we're going to cover three which are preinstalled on our attack box, ffuf, dirb and gobuster.
• Subdomain enumeration is the process of finding valid subdomains for a domain, but why do we do this? We do this to expand our attack surface to try and discover more potential points of vulnerability.

  • We will explore three different subdomain enumeration methods: Brute Force, OSINT (Open-Source Intelligence) and Virtual Host.
• SSL/TLS Certificates

  • When an SSL/TLS (Secure Sockets Layer/Transport Layer Security) certificate is created for a domain by a CA (Certificate Authority), CA's take part in what's called "Certificate Transparency (CT) logs". These are publicly accessible logs of every SSL/TLS certificate created for a domain name.
• SSL/TLS Certificates

  • The purpose of Certificate Transparency logs is to stop malicious and accidentally made certificates from being used. We can use this service to our advantage to discover subdomains belonging to a domain, sites like https://crt.sh and https://ui.ctsearch.entrust.com/ui/ctsearchui offer a searchable database of certificates that shows current and historical results.
• Search Engines

  • Search engines contain trillions of links to more than a billion websites, which can be an excellent resource for finding new subdomains. Using advanced search methods on websites like Google, such as the site: filter, can narrow the search results. For example, "-site:www.domain.com site:*.domain.com" would only contain results leading to the domain name domain.com but exclude any links to www.domain.com; therefore, it shows us only subdomain names belonging to domain.com.
• Bruteforce DNS (Domain Name System) enumeration is the method of trying tens, hundreds, thousands or even millions of different possible subdomains from a pre-defined list of commonly used subdomains. Because this method requires many requests, we automate it with tools to make the process quicker. In this instance, we are using a tool called dnsrecon to perform this.
• Automation Using Sublist3r

  • To speed up the process of OSINT subdomain discovery, we can automate the above methods with the help of tools like Sublist3r,
• Subdomains:

  • Some subdomains aren't always hosted in publically accessible DNS results, such as development versions of a web application or administration portals. Instead, the DNS record could be kept on a private DNS server or recorded on the developer's machines in their /etc/hosts file (or c:\windows\system32\drivers\etc\hosts file for Windows users) which maps domain names to IP addresses. 
• Domains:

  • Because web servers can host multiple websites from one server when a website is requested from a client, the server knows which website the client wants from the Host header. We can utilise this host header by making changes to it and monitoring the response to see if we've discovered a new website.
  • Like with DNS Bruteforce, we can automate this process by using a wordlist of commonly used subdomains.