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Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') in xwiki-platform-tag-ui

Critical
surli published GHSA-2g5c-228j-p52x Sep 8, 2022

Package

maven org.xwiki.platform:xwiki-application-tag (Maven)

Affected versions

>= 1.7

Patched versions

None
maven org.xwiki.platform:xwiki-platform-tag-ui (Maven)
< 13.10.6, < 14.4
13.10.6,14.4

Description

Impact

The tags document Main.Tags in XWiki didn't sanitize user inputs properly, allowing users with view rights on the document (default in a public wiki or for authenticated users on private wikis) to execute arbitrary Groovy, Python and Velocity code with programming rights. This allows bypassing all rights checks and thus both modification and disclosure of all content stored in the XWiki installation. Also, this could be used to impact the availability of the wiki. Some versions of XWiki XML-escaped the tag (e.g., version 3.1) but this isn't a serious limitation as string literals can be delimited by / in Groovy and < and > aren't necessary, e.g., to elevate privileges of the current user.

On XWiki versions before 13.10.4 and 14.2, this can be combined with the authentication bypass using the login action, meaning that no rights are required to perform the attack. The following URL demonstrates the attack: <server>/xwiki/bin/login/Main/Tags?xpage=view&do=viewTag&tag=%7B%7Basync+async%3D%22true%22+cached%3D%22false%22+context%3D%22doc.reference%22%7D%7D%7B%7Bgroovy%7D%7Dprintln%28%22hello+from+groovy%21%22%29%7B%7B%2Fgroovy%7D%7D%7B%7B%2Fasync%7D%7D, where <server> is the URL of the XWiki installations.

On current versions (e.g, 14.3), the issue can be exploited by requesting the URL <server>/xwiki/bin/view/Main/Tags?do=viewTag&tag=%7B%7Basync%20async%3D%22true%22%20cached%3D%22false%22%20context%3D%22doc.reference%22%7D%7D%7B%7Bgroovy%7D%7Dprintln(%22hello%20from%20groovy!%22)%7B%7B%2Fgroovy%7D%7D%7B%7B%2Fasync%7D%7D, where <server> is the URL of the server. On XWiki 2.0 (that contains version 1.7 of the tag application), the URL <server>/xwiki/bin/view/Main/Tags?do=viewTag&tag={{/html}}{{groovy}}println(%2Fhello from groovy!%2F){{%2Fgroovy}} demonstrates the exploit while on XWiki 3.1 the following URL demonstrates the exploit: <server>/xwiki/bin/view/Main/Tags?do=viewTag&tag={{/html}}{{footnote}}{{groovy}}println(%2Fhello%20from%20groovy!%2F){{%2Fgroovy}}{{/footnote}}.

Patches

This has been patched in the supported versions 13.10.6 and 14.4.

Workarounds

The patch that fixes the issue can be manually applied to the document Main.Tags or the updated version of that document can be imported from version 14.4 of xwiki-platform-tag-ui using the import feature in the administration UI on XWiki 10.9 and later (earlier versions might not be compatible with the current version of the document).

References

For more information

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Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVE ID

CVE-2022-36100

Weaknesses