Comprehensive Technical Analysis of CVE-2025-62877

CVE ID: CVE-2025-62877 CVSS Score: 9.8 (Critical) Affected Software: SUSE Harvester (1.5.x, 1.6.x) Vulnerability Type: Default Credential Exposure

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1. Vulnerability Assessment and Severity Evaluation

Vulnerability Overview

CVE-2025-62877 is a critical authentication bypass vulnerability in SUSE Harvester, a Kubernetes-based hyperconverged infrastructure (HCI) solution. The flaw arises when the interactive installer (used for cluster creation or node addition) inadvertently exposes the default SSH login credentials of the underlying host operating system.

Severity Justification (CVSS 9.8)

The CVSS v3.1 scoring breakdown is as follows:

• Attack Vector (AV:N) – Network exploitable (remote access possible).
• Attack Complexity (AC:L) – Low (no specialized conditions required).
• Privileges Required (PR:N) – None (unauthenticated access).
• User Interaction (UI:N) – None (fully automated exploitation possible).
• Scope (S:C) – Changed (impacts host OS beyond the Harvester environment).
• Confidentiality (C:H) – High (full system access via SSH).
• Integrity (I:H) – High (arbitrary command execution).
• Availability (A:H) – High (potential for denial-of-service or ransomware).

Rationale for Critical Rating:

• Unauthenticated remote access to privileged SSH credentials.
• Full system compromise (root-level access to host OS).
• Lateral movement potential within the Harvester cluster.
• No user interaction required for exploitation.

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2. Potential Attack Vectors and Exploitation Methods

Exploitation Scenarios

1. Network-Based Exploitation

   • An attacker with network access to the Harvester management interface (or exposed SSH port) can:
     • Brute-force or guess the default SSH credentials (if not rotated post-installation).
     • Intercept credentials if transmitted in plaintext during installation (e.g., via MITM attacks).
     • Exploit misconfigured firewalls allowing SSH access from untrusted networks.

2. Supply Chain & Post-Installation Attacks

   • If the default credentials persist after installation, attackers can:
     • Gain persistent access to the host OS.
     • Escalate privileges within the Harvester cluster (e.g., via Kubernetes API abuse).
     • Deploy malware (e.g., cryptominers, ransomware, or backdoors).

3. Insider Threat & Credential Theft

   • Legitimate users (e.g., admins, developers) may inadvertently expose credentials via:
     • Log files (if installation logs are not sanitized).
     • Configuration files (e.g., cloud-init or Harvester manifests).
     • Shared documentation (e.g., runbooks, internal wikis).

Exploitation Steps (Proof of Concept)

1. Identify Target System

   • Scan for Harvester nodes (e.g., via nmap -p 22 --script ssh-auth-methods <target>).
   • Check for default SSH banner (e.g., SSH-2.0-OpenSSH_8.8 on SUSE).

2. Attempt Default Credential Login

   • Common default credentials in SUSE environments:
     • root:linux
     • root:suse
     • harvester:harvester
   • If credentials are not rotated, remote SSH access is granted.

3. Post-Exploitation Actions

   • Dump Kubernetes secrets (kubectl get secrets -A).
   • Deploy malicious workloads (e.g., kubectl apply -f malicious-pod.yaml).
   • Pivot to other nodes (e.g., via ssh or scp to internal IPs).
   • Exfiltrate data (e.g., via curl, nc, or cloud storage).

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3. Affected Systems and Software Versions

Impacted Versions

Software	Affected Versions	Fixed Versions	Workaround Available?
SUSE Harvester	1.5.x, 1.6.x	1.7.0+	Yes (PXE boot + config)

Non-Affected Scenarios

• PXE Boot + Harvester Configuration Setup (automated, non-interactive).
• Manual SSH key-based authentication (if enforced post-installation).
• Air-gapped or hardened deployments (where default credentials are disabled).

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4. Recommended Mitigation Strategies

Immediate Actions (For Affected Deployments)

1. Rotate Default SSH Credentials

   • Change root password on all Harvester nodes:

     passwd root
     

   • Disable password authentication (enforce SSH keys):

     sed -i 's/PasswordAuthentication yes/PasswordAuthentication no/' /etc/ssh/sshd_config
     systemctl restart sshd
     

2. Isolate Harvester Management Network

   • Restrict SSH access to trusted subnets (e.g., via iptables or cloud security groups).
   • Disable SSH on public interfaces (bind to internal IPs only).

3. Audit and Remediate Exposed Systems

   • Scan for default credentials using tools like:
     • hydra -l root -P /path/to/passwords.txt ssh://<target>
     • nmap --script ssh-brute <target>
   • Check for unauthorized SSH sessions:

     last | grep -i "still logged in"
     

Long-Term Mitigations

1. Upgrade to Harvester 1.7.0+

   • Apply patches from SUSE to remove default credential exposure in the installer.

2. Enforce Automated Installations (PXE Boot)

   • Use non-interactive installation methods to prevent credential leakage.
   • Example cloud-init configuration:

     #cloud-config
     ssh_pwauth: false
     users:
       - name: harvester
         ssh-authorized-keys:
           - ssh-rsa AAAAB3NzaC1yc2E...
     

3. Implement Zero Trust Networking

   • Micro-segmentation (e.g., Calico, Cilium) to limit lateral movement.
   • Multi-factor authentication (MFA) for SSH access (e.g., google-authenticator).

4. Monitor for Suspicious Activity

   • SIEM integration (e.g., Splunk, ELK) to detect:
     • Multiple failed SSH login attempts.
     • Unusual sudo or kubectl commands.
   • File integrity monitoring (FIM) (e.g., AIDE, Tripwire) to detect unauthorized changes.

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5. Impact on the Cybersecurity Landscape

Broader Implications

1. Increased Attack Surface for HCI Environments

   • Harvester is widely used in edge computing, IoT, and hybrid cloud deployments.
   • Default credential vulnerabilities amplify risks in distributed systems.

2. Supply Chain Risks

   • Third-party integrations (e.g., Rancher, Longhorn) may inherit this vulnerability.
   • Misconfigured CI/CD pipelines could expose credentials in logs or artifacts.

3. Ransomware and Cryptojacking Threats

   • Kubernetes clusters are prime targets for cryptominers (e.g., XMRig) and ransomware (e.g., LockBit, BlackCat).
   • Lateral movement from a single node can lead to full cluster compromise.

4. Compliance and Regulatory Risks

   • Violations of NIST SP 800-53 (AC-2, IA-5) for credential management.
   • GDPR, HIPAA, or PCI DSS penalties if sensitive data is exfiltrated.

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6. Technical Details for Security Professionals

Root Cause Analysis

• Interactive Installer Flaw

  • The Harvester installer (1.5.x/1.6.x) temporarily stores or logs the default SSH password in:
    • Installation logs (/var/log/harvester-install.log).
    • Cloud-init configurations (/var/lib/cloud/instance/user-data.txt).
    • Systemd service files (if credentials are passed as environment variables).

• PXE Boot Workaround

  • The PXE-based installation avoids this issue by:
    • Not prompting for credentials interactively.
    • Using pre-configured SSH keys (if specified in the Harvester config).

Exploitation Indicators (IOCs)

Indicator	Description
Failed password for root	Logs in /var/log/auth.log indicating brute-force attempts.
Accepted password for root	Successful SSH login with default credentials.
kubectl get pods -A	Unauthorized Kubernetes API access (post-exploitation).
crontab -l	Persistence mechanisms (e.g., scheduled tasks).
netstat -tulnp	Unusual outbound connections (e.g., C2 servers).

Detection and Hunting Queries

1. SIEM Query (Splunk Example)

   index=os sourcetype=linux_secure "Accepted password for root" OR "Failed password for root"
   | stats count by src_ip, user, _time
   | where count > 5
   

2. YARA Rule for Malicious SSH Keys

   rule Detect_Harvester_Default_SSH_Keys {
       meta:
           description = "Detects default SSH keys in Harvester environments"
           author = "Security Team"
           reference = "CVE-2025-62877"
       strings:
           $default_key = "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQ..." // Replace with actual default key
       condition:
           $default_key
   }
   

3. Kubernetes Audit Log Check

   kubectl get events --all-namespaces | grep -i "unauthorized"
   

Forensic Analysis Steps

1. Check for Persistence

   ls -la /etc/cron* /etc/init.d/ /etc/systemd/system/
   

2. Review SSH Access Logs

   grep "Accepted" /var/log/auth.log
   

3. Inspect Running Processes

   ps auxf | grep -i "ssh\|nc\|curl\|wget"
   

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Conclusion

CVE-2025-62877 represents a critical security risk due to its low attack complexity, high impact, and unauthenticated exploitation vector. Organizations using SUSE Harvester 1.5.x/1.6.x must immediately rotate credentials, upgrade to 1.7.0+, and enforce automated installation methods to mitigate exposure.

Key Takeaways for Security Teams: ✅ Rotate all default SSH credentials post-installation. ✅ Disable password-based SSH authentication in favor of key-based auth. ✅ Monitor for brute-force attempts and unauthorized access. ✅ Upgrade to Harvester 1.7.0+ to eliminate the root cause. ✅ Implement zero-trust networking to limit lateral movement.

Failure to address this vulnerability could lead to full cluster compromise, data exfiltration, and ransomware attacks. Proactive remediation is essential to maintain the security of Harvester-based infrastructures.