CAPEC-86: XSS Through HTTP Headers
CAPEC版本: 3.9
更新日期: 2023-01-24
攻击模式描述
An adversary exploits web applications that generate web content, such as links in a HTML page, based on unvalidated or improperly validated data submitted by other actors. XSS in HTTP Headers attacks target the HTTP headers which are hidden from most users and may not be validated by web applications.
执行流程
步骤 1 Explore
[Survey the application for public links] Using a browser or an automated tool, an adversary follows all public links on a web site. They record all the entry points (input) that becomes part of generated HTTP header (not only GET/POST/COOKIE, but also Content-Type, etc.)
- Use a spidering tool to follow and record all links and analyze the web pages to find entry points. Make special note of any links that include parameters used in the HTTP headers.
- Look for HTML meta tags that could be injectable
- Use a proxy tool to record all links visited during a manual traversal of the web application.
- Use a browser to manually explore the website and analyze how it is constructed. Many browsers' plugins are available to facilitate the analysis or automate the discovery.
步骤 2 Experiment
[Probe identified potential entry points for XSS vulnerability]
- Manually inject various script payloads into each identified entry point using a list of common script injection probes and observe system behavior to determine if script was executed.
- Use an automated injection attack tool to inject various script payloads into each identified entry point using a list of common script injection probes and observe system behavior to determine if script was executed.
- Use a proxy tool to record results of manual input of XSS probes in known URLs.
步骤 3 Experiment
[Craft malicious XSS URL] Once the adversary has determined which parameters are vulnerable to XSS, they will craft a malicious URL containing the XSS exploit. The adversary can have many goals, from stealing session IDs, cookies, credentials, and page content from the victim.
- Change a URL parameter which is used in an HTTP header to include a malicious script tag. Because it is in the header it may bypass validation.
- Send information gathered from the malicious script to a remote endpoint.
步骤 4 Exploit
[Get victim to click URL] In order for the attack to be successful, the victim needs to access the malicious URL.
- Send a phishing email to the victim containing the malicious URL. This can be hidden in a hyperlink as to not show the full URL, which might draw suspicion.
- Put the malicious URL on a public forum, where many victims might accidentally click the link.
前提条件
- Target software must be a client that allows scripting communication from remote hosts.
所需技能
所需资源
- The adversary must have the ability to deploy a custom hostile service for access by targeted clients and the abbility to communicate synchronously or asynchronously with client machine. The adversary must also control a remote site of some sort to redirect client and data to.
后果影响
影响范围: Confidentiality Integrity Availability
技术影响: Execute Unauthorized Commands
说明: Run Arbitrary Code
影响范围: Confidentiality
技术影响: Read Data
影响范围: Confidentiality Access Control Authorization
技术影响: Gain Privileges
缓解措施
Design: Use browser technologies that do not allow client side scripting.
Design: Utilize strict type, character, and encoding enforcement
Design: Server side developers should not proxy content via XHR or other means, if a http proxy for remote content is setup on the server side, the client's browser has no way of discerning where the data is originating from.
Implementation: Ensure all content that is delivered to client is sanitized against an acceptable content specification.
Implementation: Perform input validation for all remote content.
Implementation: Perform output validation for all remote content.
Implementation: Disable scripting languages such as JavaScript in browser
Implementation: Session tokens for specific host
Implementation: Patching software. There are many attack vectors for XSS on the client side and the server side. Many vulnerabilities are fixed in service packs for browser, web servers, and plug in technologies, staying current on patch release that deal with XSS countermeasures mitigates this.
示例实例
XSS can be used in variety of ways, because it is scripted and executes in a distributed, asynchronous fashion it can create its own vector and openings. For example, the adversary can use XSS to mount a DDoS attack by having series of different computers unknowingly executing requests against a single host.