openssh-vulnerability-assessment

Professional cybersecurity assessment demonstrating vulnerability identification, CVSS severity scoring, MITRE ATT&CK framework application, and detailed remediation planning for OpenSSH 6.6.1p1 critical vulnerabilities (CVE-2016-0777, CVE-2015-5600)

🛡️ OpenSSH 6.6.1p1 Vulnerability Assessment

A professional security vulnerability assessment demonstrating identification, analysis, and remediation of an outdated OpenSSH service.

📋 Assessment Overview

Assessment Date: September 28, 2023
Target System: 10.10.3.31
Scanner Used: Nmap 7.91

🔍 Executive Summary

During a routine network security assessment, a critical vulnerability was identified on the target system running an outdated version of OpenSSH (6.6.1p1). This version, released in 2014, contains multiple known security vulnerabilities that could allow attackers to:

• Extract sensitive authentication credentials
• Bypass authentication mechanisms
• Gain unauthorized remote access
• Compromise system integrity

Overall Risk Rating: 🔴 HIGH

📊 Key Finding

Outdated OpenSSH Version - 6.6.1p1

Property	Value
Severity	High
CVSS Score	7.5+
Impact	High - Remote system compromise possible
Likelihood	High - Publicly accessible with known exploits
Service	SSH (Port 22/tcp)
Status	⚠️ Requires Immediate Remediation

Critical Vulnerabilities Identified

1. CVE-2016-0777 - Information Disclosure (CVSS 4.3)

   • Memory leak in roaming_common.c
   • Allows extraction of private SSH keys

2. CVE-2016-0778 - Information Disclosure (CVSS 4.3)

   • Buffer overflow in roaming code
   • Potential credential leakage

3. CVE-2015-5600 - Authentication Bypass (CVSS 8.5)

   • MaxAuthTries limit bypass
   • Enables effective brute-force attacks

4. CVE-2015-6564 - Use-After-Free (CVSS 6.5)

   • Memory corruption vulnerability
   • Potential for denial of service or code execution

🎯 Technical Analysis

Scan Results

PORT     STATE  SERVICE        VERSION
22/tcp   open   ssh            OpenSSH 6.6.1p1 Ubuntu 2ubuntu2.13

Security Implications

Authentication & Access Control:

• Vulnerable to brute-force attacks due to MaxAuthTries bypass
• Potential for unauthorized remote access
• Risk of credential theft through information disclosure

Data Confidentiality:

• Private key extraction possible through memory leaks
• Authentication data exposure during transmission
• Potential for man-in-the-middle attacks with stolen credentials

System Integrity:

• Complete system compromise through escalated access
• Lateral movement within network infrastructure
• Persistent backdoor installation risk

Attack Scenarios

1. Scenario 1: Credential Theft

   • Attacker sets up malicious SSH server
   • Client connects using vulnerable version
   • CVE-2016-0777 exploited to extract private keys
   • Attacker gains persistent access

2. Scenario 2: Brute Force

   • Attacker bypasses MaxAuthTries using CVE-2015-5600
   • Automated password guessing becomes feasible
   • Weak passwords successfully compromised
   • Unauthorized administrative access achieved

🛠️ Remediation Steps

Immediate Actions (Priority: Critical)

1. Upgrade OpenSSH to Latest Version

sudo apt update
sudo apt upgrade openssh-server openssh-client
ssh -V  # Verify upgrade

2. Harden SSH Configuration (/etc/ssh/sshd_config)

# Disable root login
PermitRootLogin no

# Enforce key-based authentication
PubkeyAuthentication yes
PasswordAuthentication no

# Limit authentication attempts
MaxAuthTries 3

# Use strong ciphers only
Ciphers [email protected],[email protected]

# Restart service
sudo systemctl restart sshd

3. Implement Additional Security Controls

• Install and configure fail2ban for brute-force protection
• Restrict SSH access via firewall rules (allow specific IPs only)
• Enable two-factor authentication (2FA)
• Monitor SSH logs for suspicious activity

📈 MITRE ATT&CK Mapping

Techniques Used by Attackers

Technique ID	Name	Description
T1021.004	Remote Services: SSH	Adversaries exploit SSH for remote access
T1110	Brute Force	Password guessing attacks
T1595.002	Vulnerability Scanning	Identifying vulnerable SSH versions

Recommended Mitigations

Mitigation ID	Name	Implementation
M1051	Update Software	Upgrade to latest OpenSSH version
M1032	Multi-factor Authentication	Implement 2FA for SSH access
M1035	Network Segmentation	Restrict SSH to management network

📚 References & Resources

CVE Details

• CVE-2016-0777 - OpenSSH Information Disclosure
• CVE-2016-0778 - OpenSSH Buffer Overflow
• CVE-2015-5600 - Authentication Bypass
• CVE-2015-6564 - Use-After-Free

Security Standards

• MITRE ATT&CK - SSH Technique
• OpenSSH Security Advisories
• NIST Guidelines for SSH

Classification Framework:

• Impact: High (complete system compromise possible)
• Likelihood: High (publicly accessible, known exploits)
• Overall Severity: High (7.0-8.9 CVSS range)

Assessment Process:

1. Network reconnaissance and port scanning
2. Service enumeration and version detection
3. Vulnerability identification via CVE database
4. Risk analysis using impact × likelihood matrix
5. Remediation planning with MITRE ATT&CK mapping

📄 Full Report

View Complete Vulnerability Report

🏆 Skills Demonstrated

✅ Network security assessment
✅ Vulnerability identification and analysis
✅ CVSS severity scoring
✅ MITRE ATT&CK framework application
✅ Professional security documentation
✅ Risk assessment and prioritization
✅ Remediation planning and guidance

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About This Assessment

This vulnerability assessment demonstrates professional cybersecurity analysis skills including:

• Technical Analysis - Identifying and assessing security vulnerabilities
• Risk Management - Evaluating business impact and likelihood
• Communication - Translating technical findings into actionable recommendations
• Industry Standards - Applying CVSS, MITRE ATT&CK, and professional methodologies

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