CVE-2023-37462: XWiki Platform RCE Vulnerability

CVE-2023-37462 Overview

CVE-2023-37462 is a critical code injection vulnerability in XWiki Platform, a generic wiki platform offering runtime services for applications built on top of it. The vulnerability stems from improper escaping in the document SkinsCode.XWikiSkinsSheet, which leads to an injection vector that can escalate from view rights to programming rights. This allows attackers to execute arbitrary script macros including Groovy and Python macros that enable remote code execution with unrestricted read and write access to all wiki contents.

Critical Impact

This vulnerability allows authenticated attackers with low privileges to achieve remote code execution with full read/write access to all wiki contents through crafted page names containing malicious payloads.

Affected Products

• XWiki Platform versions prior to 14.4.8
• XWiki Platform versions 14.5.x through 14.10.3
• XWiki Platform versions 15.0-milestone-1 through 15.0-milestone-7

Discovery Timeline

• 2023-07-14 - CVE-2023-37462 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-37462

Vulnerability Analysis

This vulnerability is classified as CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly referred to as an injection vulnerability. The flaw exists in the SkinsCode.XWikiSkinsSheet document where user-controlled input is not properly escaped before being processed by the XWiki rendering engine.

The attack mechanism exploits the way XWiki handles page names when rendering skin templates. By crafting a URL to a non-existing page with a specially constructed name containing malicious payload, an attacker can inject arbitrary script macros. Since XWiki supports powerful scripting languages like Groovy and Python through its macro system, successful exploitation grants the attacker programming-level privileges on the wiki instance.

Root Cause

The root cause is improper input sanitization in the SkinsCode.XWikiSkinsSheet document. When processing page names, the document fails to properly escape special characters and macro syntax before rendering. This allows attackers to embed executable macro code within the page name parameter, which is then interpreted and executed by the XWiki rendering engine with elevated privileges.

Attack Vector

The attack is executed over the network and requires only low-level authentication (view rights on the vulnerable document). No user interaction is required beyond the attacker accessing a crafted URL. The exploitation process involves:

1. An attacker with basic view access to the XWiki instance identifies the vulnerable SkinsCode.XWikiSkinsSheet document
2. The attacker crafts a URL pointing to a non-existing page with a name containing embedded Groovy or Python macro code
3. When the page is accessed, the XWiki rendering engine processes the malicious page name without proper escaping
4. The injected macro code executes with programming rights, allowing arbitrary code execution on the server

The vulnerability allows direct escalation from view rights to programming rights, bypassing normal permission checks. For detailed technical information and instructions on testing whether an installation is vulnerable, refer to the GitHub Security Advisory.

Detection Methods for CVE-2023-37462

Indicators of Compromise

• Unusual page access logs showing requests to non-existing pages with abnormally long or encoded page names
• Server logs containing Groovy or Python execution errors originating from skin rendering operations
• Evidence of unauthorized wiki content modifications or data exfiltration
• Unexpected outbound network connections from the XWiki server process

Detection Strategies

• Monitor web server access logs for requests containing encoded macro syntax in URL paths (e.g., {{groovy}}, {{python}})
• Implement Web Application Firewall (WAF) rules to detect and block requests with suspicious macro patterns in page name parameters
• Review XWiki audit logs for unexpected privilege escalations or programming-level operations from low-privilege users
• Deploy endpoint detection solutions to monitor for suspicious process spawning from the XWiki application server

Monitoring Recommendations

• Enable verbose logging on the XWiki platform to capture detailed request information for forensic analysis
• Configure alerts for any access to the SkinsCode.XWikiSkinsSheet document from untrusted sources
• Implement network monitoring to detect unusual outbound connections that may indicate post-exploitation activity
• Regularly audit wiki content and user permissions for unauthorized changes

How to Mitigate CVE-2023-37462

Immediate Actions Required

• Upgrade XWiki Platform to version 14.4.8, 14.10.4, or 15.0-rc-1 or later immediately
• If immediate upgrade is not possible, manually apply the fix commit d9c88ddc to the SkinsCode.XWikiSkinsSheet document
• Review access logs and wiki content for signs of prior exploitation
• Restrict network access to the XWiki instance until patching is complete

Patch Information

XWiki has released patched versions addressing this vulnerability. Users should upgrade to one of the following versions:

• XWiki 14.4.8 - For users on the 14.4.x branch
• XWiki 14.10.4 - For users on the 14.10.x branch
• XWiki 15.0-rc-1 - For users ready to adopt the 15.x branch

The fix is contained in commit d9c88ddc4c0c78fa534bd33237e95dea66003d29. For detailed patch information, consult the GitHub Commit Reference and the XWiki Jira Issue XWIKI-20457.

Workarounds

• Manually apply the fix commit d9c88ddc directly to the impacted document SkinsCode.XWikiSkinsSheet following the changes in the commit
• Implement strict WAF rules to filter requests containing script macro syntax in URL parameters
• Temporarily restrict access to the XWiki instance to trusted users only until the patch can be applied
• Consider placing the XWiki instance behind a VPN or additional authentication layer to limit exposure

# Verify XWiki version to check vulnerability status
# Check your current XWiki version in the Administration panel
# Upgrade to patched version:
# - 14.4.8 or later for 14.4.x branch
# - 14.10.4 or later for 14.10.x branch
# - 15.0-rc-1 or later for 15.x branch