Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network.
Microsoft Office SharePoint is vulnerable to a Cross-Site Scripting (XSS) attack, allowing attackers to inject malicious scripts into web pages viewed by other users. This can lead to spoofing, session hijacking, and the potential for complete compromise of the SharePoint environment, impacting data integrity and confidentiality.
Step 1: Payload Delivery: The attacker crafts a malicious payload, typically JavaScript code, designed to exploit the XSS vulnerability. This payload could be a simple alert box, or more sophisticated code to steal cookies, redirect users, or execute other malicious actions.
Step 2: Payload Injection: The attacker injects the malicious payload into a SharePoint web page. This can be achieved through various means, such as submitting the payload in a comment, a form field, or a document name. The specific injection point depends on the vulnerable component within SharePoint.
Step 3: Payload Storage (Optional): If the vulnerability allows for persistent XSS, the payload is stored on the SharePoint server. This means that every time a user visits the affected page, the payload will be executed.
Step 4: User Interaction: A legitimate user visits the SharePoint page containing the injected payload. This could be through a direct link, a search result, or simply browsing the site.
Step 5: Payload Execution: The user's browser executes the malicious JavaScript payload. The browser interprets the injected code as part of the SharePoint page's content.
Step 6: Attack Execution: The injected JavaScript code performs the attacker's intended actions, such as stealing cookies, redirecting the user to a phishing site, or modifying the content of the page. This could lead to session hijacking, data theft, or further compromise of the SharePoint environment.
The vulnerability stems from improper input validation and output encoding within SharePoint's web page generation process. Specifically, user-supplied data, such as comments, form submissions, or other dynamic content, is not adequately sanitized before being rendered in the browser. This allows attackers to inject malicious JavaScript code into the HTML output. The root cause is likely a missing or insufficient implementation of HTML encoding or input validation routines within the SharePoint code responsible for processing and displaying user-generated content. This allows attackers to bypass security measures and execute arbitrary code in the context of the SharePoint site, leading to XSS.