In-Depth Exploration of Exploiting AppSec Bugs in Internet-Facing Web Applications

Understanding AppSec Bugs

Application Security (AppSec) bugs are critical vulnerabilities within web applications that can be exploited by attackers. These security flaws can compromise an application's integrity, confidentiality, and availability. To exploit these bugs, attackers identify weaknesses, craft specific attack vectors, and utilize various tools and techniques. This blog will delve into common AppSec bugs, their exploitation, and prevention strategies.

Various AppSec Bug Types

SQL Injection (SQLi) Definition: SQL injection happens when an application uses user-supplied data without doing the necessary escape procedures or validation. Attackers can now alter the SQL query as a result.

Categories:

In-Band SQLi: The attacker executes and retrieves results (such as error-based and union-based SQLi) via the same communication channel.
Inferential SQL injection (also known as blind SQL injection) uses payloads and application behavior modifications to infer data from the attacker.
When in-band or inferential SQLi cannot be completed, the attacker may resort to out-of-band SQLi, which involves retrieving data via a separate channel.

Taking advantage of others:

Error-Based: Data extraction carried out by inducing practical database errors.

Union-Based: Using the UNION SQL operator to merge the outcomes of several queries.

SQL induction via blind queries: watching the timing and true/false answers to conditional queries.

Equipment:

SQL injection flaws may be automatically discovered and taken advantage of with sqlmap.
Havij: An extra SQL injection software that runs automatically.

preventing:

Through parameterized queries, it is ensured that user input is treated as data rather than code.
Object-Relational Mapping (ORM) frameworks allow for the abstraction of SQL queries.

Cross-Site Scripting (XSS): This is a security flaw where malicious scripts can be injected by attackers when an application inserts user input into web pages without properly validating or escaping the input.

Categories:

saved cross-site scripting (XSS): When additional users access the material, the malicious script saved on the server—for example, in a database—is called upon.
Reflected cross-site scripting: The script is reflected from a web server, usually through a form submission or URL.
DOM-Based XSS: The client-side code is vulnerable to manipulation of the DOM environment.
Taking advantage of:

Cookie Theft: Theft of user sessions by stealing session cookies.
Keylogging: Recording keystrokes made by users.
Phishing: Sending visitors to unsafe websites.

Instruments:

XSSer: This program finds and exploits XSS vulnerabilities automatically.
The Browser Exploitation Framework, or BeEF, takes use of security holes in browsers to take control of infected ones.

Avoidance:

• Validate and sanitize all user input as part of input validation.
• Prior to data being rendered in a browser, encode it using output encoding.
• XSS risks are reduced by the Content Security Policy (CSP), which establishes and upholds security regulations.

The term "cross-site request forgery" (CSRF) 

Refers to the technique of coercing a logged-in user into doing undesired actions on a website.

Taking advantage of:

Attacks that include deceiving the user into filling out forms or clicking on links are known as state-changing requests.

Instruments:

OWASP CSRFTester: Evaluates web apps for cross-site request forgeries.
The Burp Suite has tools for CSRF detection and exploitation.

Avoidance:

Anti-CSRF Tokens: Tokens are added to forms in order to verify that requests are valid.
SameSite Cookies: Cookies are limited to requests made from the same website.

Remote Code Execution (RCE) Vulnerabilities: RCE flaws let attackers run any code on the server.

Taking advantage of:

Injecting OS commands through susceptible inputs is known as command injection.
Injecting scripts or code that the application runs is known as code injection.

Instruments:

Metasploit: An environment for creating and running exploit programs.
Commix: Enables automated exploiting of vulnerabilities related to command injection.

Avoidance:

Validate and sanitize each and every input.
Employ secure APIs Steer clear of running code on user input.

Traversal of Directories

Attackers can access restricted directories and run commands outside of the web root by using directory traversal.

Taking advantage of:

Reading sensitive files, such as configuration and password files, is one way to access sensitive files. 

Tools:

Tools for identifying and taking advantage of directory traversal vulnerabilities are included in the Burp Suite.

Avoidance:

Validate inputs correctly and sanitize user inputs.
Employ secure APIs Restrict file access to particular directories alone.




When an application exposes internal objects to users without conducting the necessary authorization checks, it is known as Insecure Direct Object References, or IDOR for short.

Taking advantage of:

Changing URL parameters to get access to data that belongs to other people is known as "unauthorized data access."

Instruments:

Burp Suite: Allows for manual IDOR vulnerability testing.
Avoidance:

Access Controls: Make sure every user request is properly authorized.

 Methods of Discovery: Manual Code Review

manually looking over the source code to find any possible weaknesses. Error handling, access controls, input handling, and authentication logic are some of the focus areas.

Tools for Automated Scanning

Burp Suite: All-inclusive set of tools for both manual and automated web application security testing.
An open-source program called OWASP ZAP is used to identify security holes in online applications.
Automated web application security scanner, Acunetix.

Fuzzing

finding vulnerabilities by delivering erratic or unexpected inputs to application endpoints.

A prominent fuzzing tool for finding vulnerabilities in binary applications is called AFL (American Fuzzy Lop).
Peach Fuzzer: An app for finding security holes that is available for purchase.

Testing for Penetration

emulating online application attacks in order to find and take advantage of security flaws. Pen testers find vulnerabilities by combining automated technologies with manual methods.

Techniques of Exploitation

Crafting Payloads

Crafting SQL injection strings is one example of creating particular inputs or payloads to exploit vulnerabilities. For SQLi, payload building can be automated with tools like sqlmap.

Hijacking a session

use XSS or other techniques to steal session cookies in order to pretend to be a user. Session management tools in OWASP ZAP are one tool that may be used to simulate these assaults.

Escalation of Privilege

taking advantage of weaknesses to obtain more access within the program. Attackers search for weaknesses or incorrect configurations in access control systems.

Instruments and Structures

Burp Suite

a thorough web vulnerability scanner that includes manual testing tools. Proxy, scanner, invader, and repeater are among the features.

OWASP ZAP

an open-source program for identifying web application vulnerabilities. includes a number of security tools, automated scanning, and manual testing features.

sqlmap

an automated program for finding and taking advantage of SQL injection vulnerabilities. Data fetching, remote execution, and database fingerprinting are examples of capabilities.

A framework for creating, evaluating, and deploying exploits against targets is the Metasploit Framework. contains an extensive library of exploit modules for different kinds of vulnerabilities.

Wireshark

an analyzer of network protocols that tracks and records network activity. aids in recognizing questionable behavior and comprehending assault trends.

nmap

A tool for network scanning that finds hosts and services. useful for finding possible points of entry and doing reconnaissance.

Top Techniques

Frequent evaluations of security

Perform routine audits and security evaluations of online applications. To address vulnerabilities in software, apply updates and patches.

Lifecycle of Secure Development (SDLC)

Include security procedures in every stage of the development process. Do testing and security checks while the project is being developed.

Instruction and Practice for Users

Educate developers on common vulnerabilities and secure coding techniques. Teach consumers how to spot social engineering and phishing scams.

Put Security Measures in Place

To defend applications against frequent attacks, make use of intrusion detection systems, web application firewalls, and other security measures.

For online applications to be secure, it is imperative to comprehend and address AppSec problems. Through vulnerability identification, suitable tool and technique utilization, and adherence to best practices, companies can safeguard their applications against intrusions and guarantee their availability, integrity, and confidentiality.

WRITTEN BY :- DHRUV PRUTHI