CVE-2014-4172 – This CVE describes a URL parameter injection vu... (How to Fix)

Q: What is the severity of CVE-2014-4172?

CVE-2014-4172 has a CVSS score of 9.8 (CRITICAL). This CVE describes a URL parameter injection vulnerability in multiple CAS client implementations that allows remote attackers to inject arbitrary web script or HTML. Attackers can exploit this by manipulating service or pgtUrl parameters during ticket validation, potentially leading to cross-site scripting (XSS) or other client-side attacks. Organizations using affected versions of Jasig Java CAS Client, .NET CAS Client, or phpCAS are vulnerable.

📋 TL;DR

This CVE describes a URL parameter injection vulnerability in multiple CAS client implementations that allows remote attackers to inject arbitrary web script or HTML. Attackers can exploit this by manipulating service or pgtUrl parameters during ticket validation, potentially leading to cross-site scripting (XSS) or other client-side attacks. Organizations using affected versions of Jasig Java CAS Client, .NET CAS Client, or phpCAS are vulnerable.

💻 Affected Systems

Products:

Jasig Java CAS Client
.NET CAS Client
phpCAS

Versions: Java CAS Client before 3.3.2, .NET CAS Client before 1.0.2, phpCAS before 1.3.3

Operating Systems: All

Default Config Vulnerable: ⚠️ Yes

Notes: Affects all deployments using vulnerable versions regardless of configuration. The vulnerability is in the core validation logic.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution via XSS leading to session hijacking, credential theft, or complete compromise of user accounts and application data.

🟠

Likely Case

Cross-site scripting attacks that steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users.

🟢

If Mitigated

Limited impact with proper input validation, output encoding, and security headers in place, though the vulnerability still exists at the protocol level.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploitation requires sending specially crafted parameters to the CAS validation endpoint, which is typically accessible without authentication.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Java CAS Client 3.3.2+, .NET CAS Client 1.0.2+, phpCAS 1.3.3+

Vendor Advisory: https://github.com/Jasig/dotnet-cas-client/commit/f0e030014fb7a39e5f38469f43199dc590fd0e8d

Restart Required: Yes

Instructions:

1. Identify affected CAS client implementation. 2. Update to patched version: Java CAS Client to 3.3.2+, .NET CAS Client to 1.0.2+, or phpCAS to 1.3.3+. 3. Restart application servers. 4. Test CAS authentication functionality.

🔧 Temporary Workarounds

Input Validation Filter

all

Implement server-side validation to reject malicious service and pgtUrl parameters containing script tags or special characters.

Implement regex validation in application code: ^[a-zA-Z0-9:/.-?=&]+$ for service URLs

WAF Rule

all

Deploy web application firewall rules to block requests containing script injection patterns in CAS validation parameters.

ModSecurity rule: SecRule ARGS_NAMES "^(service|pgtUrl)$" "phase:2,deny,id:1001,msg:'CAS parameter injection attempt',t:urlDecode,t:htmlEntityDecode,t:lowercase,chain"
SecRule ARGS "<script" "t:urlDecode,t:htmlEntityDecode"

🧯 If You Can't Patch

Implement strict input validation and output encoding for all CAS validation endpoints
Deploy a reverse proxy with security filtering for CAS validation requests

🔍 How to Verify

Check if Vulnerable:

Check application dependencies for affected CAS client versions. For Java: examine pom.xml or build.gradle for cas-client-core < 3.3.2. For .NET: check packages.config for DotNetCasClient < 1.0.2. For PHP: check composer.json for phpCAS < 1.3.3.

Check Version:

Java: mvn dependency:tree | grep cas-client-core; .NET: Get-Package | Where-Object {$_.Id -like '*cas*'}; PHP: composer show | grep phpCAS

Verify Fix Applied:

Confirm updated versions: Java CAS Client ≥3.3.2, .NET CAS Client ≥1.0.2, or phpCAS ≥1.3.3. Test CAS authentication with various service URLs to ensure validation works without errors.

📡 Detection & Monitoring

Log Indicators:

Unusual service parameter values in CAS validation logs
pgtUrl parameters containing script tags or unusual characters
Multiple failed validation attempts with malformed URLs

Network Indicators:

HTTP requests to /cas/validate with suspicious parameters
Unusual parameter lengths in CAS validation endpoints
Requests containing <script> tags in URL parameters

SIEM Query:

source="cas.log" AND (service="*<script*" OR pgtUrl="*<script*")

📊 Metadata

CVE ID: CVE-2014-4172

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-74

Published: January 24, 2020

Last Updated: November 21, 2024

🔗 References

http://lists.fedoraproject.org/pipermail/package-announce/2014-August/137182.html Third Party Advisory
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=759718 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1131350 Issue Tracking,Third Party Advisory
https://exchange.xforce.ibmcloud.com/vulnerabilities/95673 Third Party Advisory,VDB Entry
https://github.com/Jasig/dotnet-cas-client/commit/f0e030014fb7a39e5f38469f43199dc590fd0e8d Patch,Third Party Advisory
https://github.com/Jasig/java-cas-client/commit/ae37092100c8eaec610dab6d83e5e05a8ee58814 Patch,Third Party Advisory
https://github.com/Jasig/phpCAS/blob/master/docs/ChangeLog Release Notes,Third Party Advisory
https://github.com/Jasig/phpCAS/pull/125 Third Party Advisory
https://issues.jasig.org/browse/CASC-228 Third Party Advisory
https://www.debian.org/security/2014/dsa-3017.en.html Third Party Advisory
https://www.mail-archive.com/cas-user%40lists.jasig.org/msg17338.html
http://lists.fedoraproject.org/pipermail/package-announce/2014-August/137182.html Third Party Advisory
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=759718 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1131350 Issue Tracking,Third Party Advisory
https://exchange.xforce.ibmcloud.com/vulnerabilities/95673 Third Party Advisory,VDB Entry
https://github.com/Jasig/dotnet-cas-client/commit/f0e030014fb7a39e5f38469f43199dc590fd0e8d Patch,Third Party Advisory
https://github.com/Jasig/java-cas-client/commit/ae37092100c8eaec610dab6d83e5e05a8ee58814 Patch,Third Party Advisory
https://github.com/Jasig/phpCAS/blob/master/docs/ChangeLog Release Notes,Third Party Advisory
https://github.com/Jasig/phpCAS/pull/125 Third Party Advisory
https://issues.jasig.org/browse/CASC-228 Third Party Advisory
https://www.debian.org/security/2014/dsa-3017.en.html Third Party Advisory
https://www.mail-archive.com/cas-user%40lists.jasig.org/msg17338.html

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