CVE-2023-25267 – This vulnerability allows authenticated attacke... (How to Fix)

Q: What is the severity of CVE-2023-25267?

CVE-2023-25267 has a CVSS score of 8.8 (HIGH). This vulnerability allows authenticated attackers to trigger a stack-based buffer overflow in GFI Kerio Connect's webmail component by sending specially crafted requests with an overly long email address field. Successful exploitation could lead to remote code execution or denial of service. Organizations running affected versions of GFI Kerio Connect are at risk.

📋 TL;DR

This vulnerability allows authenticated attackers to trigger a stack-based buffer overflow in GFI Kerio Connect's webmail component by sending specially crafted requests with an overly long email address field. Successful exploitation could lead to remote code execution or denial of service. Organizations running affected versions of GFI Kerio Connect are at risk.

💻 Affected Systems

Products:

GFI Kerio Connect

Versions: 9.4.1 patch 1 and earlier versions (fixed in 10.0.0)

Operating Systems: All platforms running GFI Kerio Connect

Default Config Vulnerable: ⚠️ Yes

Notes: Requires authenticated access to the webmail component. The vulnerability is in the 2FA setup functionality.

📦 What is this software?

Kerio Connect by Gfi

View all CVEs affecting Kerio Connect →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with authenticated user privileges, potentially leading to complete system compromise, data exfiltration, or lateral movement within the network.

🟠

Likely Case

Denial of service causing webmail component crashes, or limited remote code execution within the application context.

🟢

If Mitigated

Application crash with no code execution if exploit fails or protections like ASLR/DEP are effective.

🌐 Internet-Facing: HIGH - The webmail component is typically internet-facing, making it accessible to attackers who can obtain valid credentials.

🏢 Internal Only: MEDIUM - Internal attackers with valid credentials could exploit this, but requires authentication.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploit requires valid authentication credentials. Public proof-of-concept demonstrates the buffer overflow trigger.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 10.0.0

Vendor Advisory: https://support.kerioconnect.gfi.com/hc/en-us/articles/9044634878226-Kerio-Connect-10-0-0-Release-Notes

Restart Required: Yes

Instructions:

1. Backup current configuration and data. 2. Download Kerio Connect 10.0.0 from official vendor site. 3. Stop Kerio Connect service. 4. Install version 10.0.0. 5. Restart Kerio Connect service. 6. Verify successful upgrade.

🔧 Temporary Workarounds

Restrict webmail API access

all

Block or restrict access to the vulnerable /webmail/api/jsonrpc endpoint using web application firewall or network controls.

Disable 2FA setup functionality

all

Temporarily disable two-factor authentication setup features if not critically needed.

🧯 If You Can't Patch

Implement strict network segmentation to isolate Kerio Connect servers from critical systems
Enforce strong authentication policies and monitor for credential compromise

🔍 How to Verify

Check if Vulnerable:

Check Kerio Connect version in admin interface. If version is 9.4.1 patch 1 or earlier, system is vulnerable.

Check Version:

Check via Kerio Connect admin web interface at /admin/ or examine installed version in control panel.

Verify Fix Applied:

Verify version shows 10.0.0 or later in admin interface. Test 2FA setup functionality with normal inputs.

📡 Detection & Monitoring

Log Indicators:

Unusually long email address fields in webmail API requests
Multiple failed 2FA setup attempts
Application crash logs mentioning webmail component

Network Indicators:

HTTP POST requests to /webmail/api/jsonrpc with abnormally long parameters
Traffic patterns showing buffer overflow attempts

SIEM Query:

source="kerio_connect" AND (uri_path="/webmail/api/jsonrpc" AND request_size>10000) OR (event="application_crash" AND process="webmail")

📊 Metadata

CVE ID: CVE-2023-25267

CVSS v3 Score: 8.8 (HIGH)

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

CWE: CWE-787

Published: March 15, 2023

Last Updated: November 21, 2024

🔗 References

https://gist.github.com/Frycos/62fa664bacd19a85235be19c6e4d7599 Exploit,Third Party Advisory
https://support.kerioconnect.gfi.com/hc/en-us/articles/9044634878226-Kerio-Connect-10-0-0-Release-Notes Release Notes
https://gist.github.com/Frycos/62fa664bacd19a85235be19c6e4d7599 Exploit,Third Party Advisory
https://support.kerioconnect.gfi.com/hc/en-us/articles/9044634878226-Kerio-Connect-10-0-0-Release-Notes Release Notes

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