Stored XSS

WHAT IS STORED XSS?

Stored cross-site scripting (XSS) is a type of attack where an attacker injects a malicious script into a web application and the application saves it. When a victim visits the page, the browser executes the malicious script. Stored XSS is also known as persistent or second-order XSS.

HOW DOES STORED XSS WORK?

1.An attacker finds a vulnerability in a web application. 

2.The attacker injects malicious code into the application, often through a user input field like a comment section. 

3.The application saves the malicious code in a database or other location. 

4.When a victim visits the infected page, the malicious code is sent to their browser. 

5.The victim's browser executes the malicious code, which can steal the victim's session information or other data. 

MITIGATION FOR STORED XSS?

1.Validate user input: Check that user input matches what the system expects. For example, you can limit the characters allowed for a phone number. 

2.Encode data: Replace HTML metacharacters with the corresponding HTML entities. 

3.Use a content security policy (CSP): A CSP blocks malicious scripts by only allowing scripts to run from specific domains. 

4.Use a vulnerability scanner: An automated scanner can test for vulnerabilities at all data entry and exit points. 

5.Use a secure coding framework: Some frameworks automatically escape HTML, making it less likely to introduce XSS vulnerabilities. 

CONCLUSION:

If an attacker can control a script that is executed in the victim's browser, then they can typically fully compromise that user. The attacker can carry out any of the actions that are applicable to the impact of reflected XSS vulnerabilities.