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CVE-2020-11103

9.8 CRITICAL
Remote Code Execution

📋 TL;DR

This vulnerability in Webswing's JsLink mechanism allows remote attackers to execute arbitrary code on affected servers. It affects Webswing installations before version 2.6.12 LTS, and versions 2.7.x and 20.x before 20.1. Any organization using vulnerable Webswing versions is at risk of complete server compromise.

💻 Affected Systems

Products:
  • Webswing
Versions: Before 2.6.12 LTS, 2.7.x before 20.1, 20.x before 20.1
Operating Systems: All platforms running Webswing
Default Config Vulnerable: ⚠️ Yes
Notes: All Webswing installations with JsLink enabled are vulnerable. JsLink is a feature that allows JavaScript execution from URLs.

📦 What is this software?

Webswing by Webswing

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Webswing by Webswing

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system takeover with administrative privileges, data exfiltration, lateral movement within network, and persistent backdoor installation.

🟠

Likely Case

Remote code execution leading to application compromise, data theft, and potential ransomware deployment.

🟢

If Mitigated

Limited impact if proper network segmentation, least privilege, and monitoring are in place, but still significant risk.

🌐 Internet-Facing: HIGH
🏢 Internal Only: HIGH

🎯 Exploit Status

Public PoC: ⚠️ Yes
Weaponized: LIKELY
Unauthenticated Exploit: ⚠️ Yes
Complexity: LOW

The vulnerability is in the JsLink mechanism which processes JavaScript from URLs, making exploitation straightforward for attackers.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 2.6.12 LTS, 20.1

Vendor Advisory: https://www.webswing.org/docs/2.6/discover/release_notes.html#release-notes-2-6-12

Restart Required: Yes

Instructions:

1. Download patched version from Webswing website. 2. Backup current installation. 3. Stop Webswing service. 4. Install patched version. 5. Restart Webswing service. 6. Verify version is updated.

🔧 Temporary Workarounds

Disable JsLink feature

all

Temporarily disable the vulnerable JsLink mechanism until patching can be completed.

Edit webswing.config file and set 'jsLinkEnabled' to false

Network isolation

linux

Restrict network access to Webswing instances using firewall rules.

iptables -A INPUT -p tcp --dport [webswing-port] -s [trusted-ips] -j ACCEPT
iptables -A INPUT -p tcp --dport [webswing-port] -j DROP

🧯 If You Can't Patch

  • Isolate Webswing instances in separate network segments with strict firewall rules
  • Implement web application firewall (WAF) rules to block suspicious JsLink patterns

🔍 How to Verify

Check if Vulnerable:

Check Webswing version in admin console or configuration files. If version is before 2.6.12 LTS, or 2.7.x/20.x before 20.1, system is vulnerable.

Check Version:

Check webswing.config file or admin interface for version information

Verify Fix Applied:

Verify Webswing version is 2.6.12 LTS or 20.1 or later. Test JsLink functionality to ensure it's properly secured.

📡 Detection & Monitoring

Log Indicators:

  • Unusual JsLink requests in access logs
  • Suspicious JavaScript execution patterns
  • Unexpected process creation from Webswing

Network Indicators:

  • Outbound connections from Webswing to unusual destinations
  • Large data transfers from Webswing server

SIEM Query:

source="webswing" AND (url="*jslink*" OR message="*JsLink*")

📊 Metadata

CVE ID: CVE-2020-11103
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
Published: December 30, 2020
Last Updated: November 21, 2024

🔗 References

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