Users can enter HTML in Blackboard Learn in a variety of ways. For example, users can enter HTML using the content editor in blogs and discussion boards, and through HTML file uploads. In the past, a security threat was introduced because users could enter potentially dangerous tags, such as script tags. Such tags could be used to execute malicious script in Blackboard Learn, exposing other users to attacks. This is referred to as cross scripting, which allows a user to have control over other user browsers.
Safe HTML filters provide you with more control over the type of HTML students can enter, making user-supplied HTML safer to use in Blackboard Learn. The feature replaces an earlier HTML sanitizer with the open-source security library from the Open Web Application Security Project's AntiSamy API. The new API ensures that user-supplied HTML complies with an application's rules.
Blackboard Learn provides administrators with a default-policy.xml file containing Safe HTML rules. Administrators can define the HTML tags and attributes in the default-policy.xml file that are allowable on their Blackboard Learn instance, based on their organization's risk tolerance level.
Safe HTML is only applicable to users who don't have the Add/Modify Trusted Content privilege, also called the Add/Edit Trusted Content With Scripts privilege. Users with this privilege can enter unrestricted/trusted HTML, meaning they aren't bound to the Safe HTML rules. By default, Blackboard Learn gives this privilege to Administrators, Course Builders, Graders, Instructors, and Teaching Assistants. All other roles don't have this privilege by default, but it can be added on an as-needed basis.
On the Administrator Panel, select Safe HTML Filters in the Security menu.
Blackboard Learn SaaS environments can't be configured to filter custom file types through HTML filters.
Customize a policy
Administrators can customize the list of allowable HTML tags and attributes in the default-policy.xml file based on the needs of their organizations. However, this should be a rare event. Administrators only need to customize the policy if they have a specific use case that the policy doesn't support.
- On the Administrator Panel, select Safe HTML Filters in the Security menu.
- Select Safe HTML Filter for Content Editor to access the policy list.
- Access the menu for the default-policy.xml and select Download. Save the file on your computer.
- Make any changes to the SafeHTML rule to meet the needs of your organization.
- When you've edited the file, type a new name.
- Return to the Safe HTML Filter for Content Editor page to access the policy list.
- Select Upload to access the Upload Safe HTML Policy page and browse for your new file.
- Optionally, type a comment.
- Select Submit to upload the new file.
- The new file appears in the list of policy files. From the file's menu, select Activate to make this the active policy file in your Blackboard Learn environment.
Test a policy
Administrators can test policies to make sure they are functioning properly and yielding the results they want.
- On the Administrator Panel, select Safe HTML Filters in the Security menu.
- Select Safe HTML Filter for Content Editor.
- From the policy file's menu, select Test Policy.
- In the Enter code (HTML, JS) to Test field, enter any HTML code that you want to test.
- Select Test.
The system provides test results, based on the HTML code entered, such as these:
- A new Sanitized Output field appears showing you the system-sanitized output for the HTML you entered.
- If the script tag you entered isn't allowed by the policy, a message appears telling you the script isn't allowed for security reasons.
- A tag may contain an attribute that can't be processed. In this case, a message appears with the tag that contains an attribute that can't be processed and has been filtered out.
HTML body tags and attributes
The default-policy.xml file allows these body tags and attributes.
Grouping elements
HTML Body Tags and Attributes
| Tag |
Attributes |
| div |
id, class, lang, dir, title, style, align |
| span |
id, class, dir, title, style, align, xml:lang |
Headings
Headings
| Tag |
Attributes |
| h1 |
id, class, lang, dir, title, style, align |
| h2 |
id, class, lang, dir, title, style, align |
| h3 |
id, class, lang, dir, title, style, align |
| h4 |
id, class, lang, dir, title, style, align |
| h5 |
id, class, lang, dir, title, style, align |
| h6 |
id, class, lang, dir, title, style, align |
Address
Address
| Tag |
Attributes |
| address |
id, class, lang, dir, title, style |
Font Style and HR Tags and Attributes
The default-policy.xml file ships with these font style and HR tags and attributes.
Font style
Font Style and HR Tags and Attributes
| Tag |
Attributes |
| tt |
id, class, lang, dir, title, style |
| i |
id, class, lang, dir, title, style |
| b |
id, class, lang, dir, title, style |
| big |
id, class, lang, dir, title, style |
| small |
id, class, lang, dir, title, style |
HR
HR
| Tag |
Attributes |
| hr |
id, class, lang, dir, title, style |
List tags and attributes
The default-policy.xml file ships with these list tags and attributes.
Unordered lists, ordered lists, and list items
List Tags and Attributes
| Tag |
Attributes |
| ul |
id, class, lang, dir, title, style |
| li |
id, class, lang, dir, title, style |
| ol |
id, class, lang, dir, title, style |
Definition lists
Definition Lists
| Tag |
Attributes |
| dl |
id, class, lang, dir, title, style |
| dt |
id, class, lang, dir, title, style |
| dd |
id, class, lang, dir, title, style |
| dir |
id, class, dir, title, style, compact |
| menu |
id, class, lang, dir, title, style, compact |
Link tags and attributes
The default-policy.xml file ships with these link tags and attributes.
Links
Link Tags and Attributes
| Tag |
Attributes |
| a |
class, dir, id, lang, name, rel, rev, style, target = _blank, title, xml:lang, accesskey, tabindex, charset, coords, href, hreflang, name, shape |
| link |
See http://www.w3schools.com/tags/tag_link.asp. |
Text tags and attributes
The default-policy.xml file ships with these text tags and attributes.
Phrase elements
Text Tags and Attributes
| Tag |
Attributes |
| em |
id, class, lang, dir, title, style |
| strong |
id, class, lang, dir, title, style |
| cite |
id, class, lang, dir, title, style |
| dfn |
id, class, lang, dir, title, style |
| code |
id, class, lang, dir, title, style |
| samp |
id, class, lang, dir, title, style |
| kbd |
id, class, lang, dir, title, style |
| var |
id, class, lang, dir, title, style |
| abbr |
id, class, lang, dir, title, style |
| acronym |
id, class, lang, dir, title, style |
Quotations
Quotation Tags and Attributes
| Tag |
Attributes |
| blockquote |
id, class, lang, dir, title, style |
| q |
id, class, lang, dir, title, style |
Subscripts and superscripts
Subscript and Superscript Tags and Attributes
| Tag |
Attributes |
| sub |
id, class, lang, dir, title, style |
| sup |
id, class, lang, dir, title, style |
Lines and paragraphs
Line and Paragraph Tags and Attributes
| Tag |
Attributes |
| p |
id, class, lang, dir, title, stye, align |
| br |
id, class, title, style, clear |
| pre |
id, class, lang, dir, title, style |
Marking document changes
Marking Document Change Tags and Attributes
| Tag |
Attributes |
| ins |
id, class, lang, dir, title, style |
| del |
id, class, lang, dir, title, style |
Table tags and attributes
The default-policy.xml file ships with these table tags and attributes.
Table
Table Tags and Attributes
| Tag |
Attributes |
| table |
id, border, cellpadding, cellspacing, align, class, frame, summary, lang, dir, style, bgcolor, width, rules, dir |
Table captions
Table Caption Tags and Attributes
| Tag |
Attributes |
| caption |
id, lang, dir, title, style |
Row groups
Row Group Tags and Attributes
| Tag |
Attributes |
| thread |
cellhalign, cellvalign, id, class, lang, dir, title, style, align, char, charoff, valign |
| tfoot |
cellhalign, cellvalign, id, class, lang, dir, title, style, align, char, charoff, valign |
| tbody |
id, class, lang, dir, title, style, align, char, charoff, valign |
| pre |
id, class, lang, dir, title, style |
Column groups
Column Group Tags and Attributes
| Tag |
Attributes |
| colgroup |
span, width, id, class, lang, dir, title, style, align, char, charoff, valign |
| col |
span, width, id, class, lang, dir, title, style, align, char, charoff, valign |
Table rows
Table Row Tags and Attributes
| Tag |
Attributes |
| tr |
id, class, lang, dir, title, style, bgcolor, align, char, charoff, valign |
Table cells
Table Cell Tags and Attributes
| Tag |
Attributes |
| th |
abbr, axis, headers, scope, rowspan, colspan, id, class, lang, dir, title, style, bgcolor, align, char, charoff, valign |
| td |
abbr, axis, headers, scope, rowspan, colspan, id, class, lang, dir, title, style, bgcolor, align, char, charoff, valign |
Embedded media and Mashup tags and attributes
The default-policy.xml file ships with these embedded media and mashup tags and attributes.
Partners
Embedded Media and Mashup Tags and Attributes
| Tag |
Attributes |
| script |
type, charset, src |
| iframe |
src=starts with SafeHTML Restricted Youtube Sources or building blocks, longdesc, name, width, height, id, class, title, style, align, frameborder, marginwidth, marginheight, scrolling |
Images
Image Tags and Attributes
| Tag |
Attributes |
| img |
src, alt, longdesc, name, id, class, lang, dir, title, style, align, width, height, border, hspace, vspace |
YouTube
YouTube Tags and Attributes
| Tag |
Attributes |
| object |
classid, codebase, codetype, data, type, archive, declare, standby, id, class, lang, dir, title, style, tabindex, name, align, width, height, border, hspace, vspace |
| param |
name=movie, value=starts with SafeHTML Restricted Youtube Sources, name = allowscriptaccess, value=true, name=allowfullscreen, value=true|false |
| embed |
src=starts with SafeHTML Restricted Youtube Sources, allowScriptAccess=never, allowNetworking=internal, type=application/x-shockwave-flash, id, width, height, type, quality, scale, salign, wmode, base, name, align, hspace, vspace, bgcolor, sound, progress, swstretchstyle, swstretchalign, swstretchvalign |
| iframe |
src=starts with http(s)://www.youtube.com or http(s)://www.youtube-nocookie.com/, longdesc, name, width, height, id, class, title, style, align, frameborder, marginwidth, marginheight, scrolling |
Slideshare
Slideshare Tags and Attributes
| Tag |
Attributes |
| object |
classid, codebase, codetype, data, type, archive, declare, standby, id, class, lang, dir, title, style, tabindex, name, align, width, height, border, hspace, vspace |
| param |
name=movie, value=starts with http(s)://static.slidesharecdn.com/ or http(s)://www.slideshare.net/, name=allowscriptaccess, value=never, name=allowfullscreen, value=true|false, name=wmode, value=transparent |
| embed |
src=starts with http(s)://static.slidesharecdn.com/ or http(s)://www.slideshare.net/, allowScriptAccess=never, allowNetworking=never, wmode=transparent, type=application/x-shockwave-flash, id, width, height, type, quality, scale, salign, base, name, align, hspace, vspace, bgcolor, sound, progress, autostart=false, swstretchstyle, swstretchalign, swstretchvalign |
| iframe |
src=starts with http(s)://static.slidesharecdn.com/ or http(s)://www.slideshare.net/, height, width, frameborder, marginwidth, marginheight, scrolling |
Other media types including Flash
Other Media Type Tags and Attributes
| Tag |
Attributes |
Comments |
| object |
codebase, name, align, hspace, vspace, bgcolor, classid |
|
| param |
name=allowScriptAccess, value=never, name=allowNetworking, value=none, name=autostart, value=false |
May contain other parameters, but these must always be present for sources other than youtube and slideshare. |
| embed |
allowScriptAccess=never, allowNetworking=none, autostart=false, allowFullScreen=false, type=... see comment, wmode=window/transparent/opaque, id, class, dir, flashvars, height, lang, name, src, style, title, width, xml:lang |
allowScriptAccess=never must always be present for Flash
allowNetworking=none must always be present for Flash
allowFullScreen=false must always be present for Flash
"type" is not restricted currently to our supported media types, but the default policy will eventually be limited to:
- video/quicktime
- application/x-shockwave-flash
- application/x-director
- application/x-mplayer2
|
| iframe |
src=restricted list, longdesc, name, width, height, id, class, title, style, align, frameborder, marginwidth, marginheight, scrolling |
|
