Failure to Sanitize Script in Attributes in a Web Page
Weakness ID: 83 (Weakness Variant)Status: Draft
+ Description

Description Summary

The software does not filter "javascript:" or other URI's from dangerous attributes within tags, such as onmouseover, onload, onerror, or style.
+ Time of Introduction
  • Implementation
+ Applicable Platforms



+ Observed Examples
CVE-2001-0520Bypass filtering of SCRIPT tags using onload in BODY, href in A, BUTTON, INPUT, and others.
CVE-2002-1493guestbook XSS in STYLE or IMG SRC attributes.
CVE-2002-1965Javascript in onerror attribute of IMG tag.
CVE-2002-1495XSS in web-based email product via onmouseover event.
CVE-2002-1681XSS via script in <P> tag.
CVE-2004-1935Onload, onmouseover, and other events in an e-mail attachment.
CVE-2005-0945Onmouseover and onload events in img, link, and mail tags.
CVE-2003-1136Javascript in onmouseover attribute in e-mail address or URL.
+ Potential Mitigations

Carefully check each input parameter against a rigorous positive specification (white list) defining the specific characters and format allowed. All input should be sanitized, not just parameters that the user is supposed to specify, but all data in the request, including tag attributes, hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. We often encounter data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.

This involves "HTML Entity Encoding" all non-alphanumeric characters from data that was received from the user and is now being written to the request.

With Struts, you should write all data from form beans with the bean's filter attribute set to true.

Additionally, to help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as Internet Explorer), this attribute prevents the user's session cookie from being accessed by client-side scripts, including scripts inserted due to a XSS attack.

+ Weakness Ordinalities
(where the weakness exists independent of other weaknesses)
+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness BaseWeakness Base79Failure to Preserve Web Page Structure ('Cross-site Scripting')
Development Concepts (primary)699
Research Concepts (primary)1000
ParentOfWeakness VariantWeakness Variant82Improper Sanitization of Script in Attributes of IMG Tags in a Web Page
Development Concepts (primary)699
Research Concepts (primary)1000
+ Causal Nature


+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERXSS using Script in Attributes
+ Related Attack Patterns
CAPEC-IDAttack Pattern Name
(CAPEC Version: 1.4)
18Embedding Scripts in Nonscript Elements
+ Content History
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Observed Example, Taxonomy Mappings, Weakness Ordinalities
2009-10-29CWE Content TeamMITREInternal
updated Relationships
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11XSS using Script in Attributes