CVE-2023-28853 – This vulnerability allows attackers to perform ... (How to Fix)

Q: What is the severity of CVE-2023-28853?

CVE-2023-28853 has a CVSS score of 7.7 (HIGH). This vulnerability allows attackers to perform LDAP injection attacks on Mastodon instances configured with LDAP authentication. By manipulating login queries, attackers can extract arbitrary attributes from the LDAP database, potentially exposing sensitive user information. Affected systems are Mastodon instances running versions 2.5.0 through 3.5.7, 4.0.0 through 4.0.3, and 4.1.0 through 4.1.1 with LDAP authentication enabled.

📋 TL;DR

This vulnerability allows attackers to perform LDAP injection attacks on Mastodon instances configured with LDAP authentication. By manipulating login queries, attackers can extract arbitrary attributes from the LDAP database, potentially exposing sensitive user information. Affected systems are Mastodon instances running versions 2.5.0 through 3.5.7, 4.0.0 through 4.0.3, and 4.1.0 through 4.1.1 with LDAP authentication enabled.

💻 Affected Systems

Products:

Mastodon

Versions: 2.5.0 through 3.5.7, 4.0.0 through 4.0.3, and 4.1.0 through 4.1.1

Operating Systems: All

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when LDAP authentication is configured and enabled. Standard email/password authentication is not affected.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete LDAP database compromise allowing extraction of all user attributes including passwords, personal information, and organizational data.

🟠

Likely Case

Extraction of user email addresses, names, roles, and other directory attributes leading to privacy violations and potential credential harvesting.

🟢

If Mitigated

Limited information disclosure if LDAP directory contains minimal sensitive attributes or proper access controls are implemented.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploitation requires knowledge of LDAP query syntax and access to login endpoint. Public proof-of-concept exists in security advisories.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 3.5.8, 4.0.4, or 4.1.2

Vendor Advisory: https://github.com/mastodon/mastodon/releases/tag/v3.5.8

Restart Required: Yes

Instructions:

1. Backup your Mastodon instance. 2. Update to Mastodon version 3.5.8, 4.0.4, or 4.1.2 using your package manager or git. 3. Run bundle install. 4. Run rails db:migrate. 5. Restart Mastodon services.

🔧 Temporary Workarounds

Disable LDAP Authentication

all

Temporarily disable LDAP authentication until patching is complete

Edit config/initializers/devise.rb and set config.ldap_authentication = false
Restart Mastodon services

🧯 If You Can't Patch

Implement network-level restrictions to limit LDAP login endpoint access to trusted IPs only
Enable detailed LDAP query logging and monitor for unusual patterns or injection attempts

🔍 How to Verify

Check if Vulnerable:

Check Mastodon version and LDAP configuration. If version is between 2.5.0-3.5.7, 4.0.0-4.0.3, or 4.1.0-4.1.1 AND LDAP is enabled, system is vulnerable.

Check Version:

cd /path/to/mastodon && git describe --tags 2>/dev/null || cat .git/refs/heads/main

Verify Fix Applied:

Verify Mastodon version is 3.5.8, 4.0.4, or 4.1.2 or higher. Confirm LDAP queries are now properly sanitized in authentication logs.

📡 Detection & Monitoring

Log Indicators:

Unusual LDAP query patterns in authentication logs
LDAP queries containing special characters like *, (, ), &, |, =
Multiple failed login attempts with LDAP injection patterns

Network Indicators:

Unusual volume of traffic to LDAP authentication endpoint
Requests containing LDAP filter syntax in login parameters

SIEM Query:

source="mastodon.logs" AND "LDAP" AND ("*" OR "(" OR ")" OR "&" OR "|") AND NOT "normalized"

📊 Metadata

CVE ID: CVE-2023-28853

CVSS v3 Score: 7.7 (HIGH)

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

CWE: CWE-90

Published: April 4, 2023

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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📋 TL;DR

💻 Affected Systems

📦 What is this software?

Mastodon by Joinmastodon

Mastodon by Joinmastodon

Mastodon by Joinmastodon

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Disable LDAP Authentication

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

🔗 Related Vulnerabilities