|Name ||Embedding Scripts within Scripts |
|Summary ||An attack of this type exploits a programs' vulnerabilities that are brought on by allowing remote hosts to execute scripts. The attacker leverages this capability to execute scripts to execute his/her own script by embedding it within other scripts that the target software is likely to execute. The attacker must have the ability to inject script into script that is likely to be executed. If this is done, then the attacker can potentially launch a variety of probes and attacks against the web server's local environment, in many cases the so-called DMZ, back end resources the web server can communicate with, and other hosts.
With the proliferation of intermediaries, such as Web App Firewalls, network devices, and even printers having JVMs and Web servers, there are many locales where an attacker can inject malicious scripts. Since this attack pattern defines scripts within scripts, there are likely privileges to execute said attack on the host.
|Prerequisites ||Target software must be able to execute scripts, and also allow attacker to write/upload script |
|Solutions ||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: 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.
Implementation: Privileges are constrained, if a script is loaded, ensure system runs in chroot jail or other limited authority mode |
|CWE ID ||Description |
|CWE-71 ||DEPRECATED: Apple '.DS_Store' |
|CWE-79 ||Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') |
|CWE-276 ||Incorrect Default Permissions |
|CWE-279 ||Incorrect Execution-Assigned Permissions |
|CWE-284 ||Improper Access Control |
|CWE-692 ||Incomplete Blacklist to Cross-Site Scripting |
|CWE-697 ||Incorrect Comparison |
|CWE-713 ||OWASP Top Ten 2007 Category A2 - Injection Flaws |