CVE-2025-26850

Executive Summary

CVE-2025-26850 is a critical privilege escalation vulnerability in the Quest KACE Systems Management Appliance (SMA) agent. The flaw allows an attacker with low-privileged access to a managed system to escalate privileges, potentially gaining full administrative control. With a CVSS score of 9.3, this vulnerability poses a severe risk to enterprise environments using KACE SMA for endpoint management. The vendor has released patches in versions 14.0.97 and 14.1.19. No public proof-of-concept (PoC) or exploit code is currently available, but the high severity and potential for lateral movement make immediate patching critical.

Supply Chain & Package Security

This vulnerability is not related to a package manager (NPM, PyPI, Go, Ruby) but is a proprietary agent-based software component. The risk is in the supply chain of managed endpoints, where a compromised agent could lead to widespread system compromise.

CVSS Breakdown & Threat Level

• CVSS Score: 9.3 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
• Attack Vector: Network (AV:N) – The vulnerability can be exploited over the network.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: Low (PR:L) – The attacker needs initial access to a managed system.
• User Interaction: None (UI:N) – No user action is needed.
• Scope: Changed (S:C) – The vulnerability can impact resources beyond the original security scope.
• Confidentiality, Integrity, Availability: High (C:H/I:H/A:H) – Full compromise of the managed system.

Threat Level: Critical. Exploitation could lead to complete takeover of managed endpoints, enabling ransomware deployment, data exfiltration, or lateral movement within the enterprise.

Deep Dive & Mechanics

The vulnerability resides in the KACE SMA agent, which runs on managed systems to communicate with the central KACE appliance. The agent performs various system management tasks, including software deployment, inventory collection, and remote command execution. The flaw is a privilege escalation issue (CWE-269) where the agent does not properly validate or restrict the execution context of certain operations.

Root Cause: The agent may execute commands or scripts with elevated privileges (e.g., SYSTEM or root) without adequate authorization checks. An attacker with low-privileged access to a managed system can craft a malicious request or manipulate agent communication to trigger execution of arbitrary code with higher privileges.

Attack Vector: The attacker must have network access to the managed system and low-privileged credentials (e.g., a standard user account). The attack likely involves sending a specially crafted message to the agent's listening service or exploiting a race condition in privilege separation.

Impact: Successful exploitation grants the attacker full administrative control over the managed system, allowing them to install malware, disable security controls, pivot to other systems, or exfiltrate sensitive data.

Vulnerable vs. Patched Code

Since no specific code diff is publicly available, the following is a hypothetical analysis based on common privilege escalation patterns.

Vulnerable Code (Hypothetical):

// Agent receives a command from the KACE server
void execute_command(char *command) {
    // No privilege check - runs as SYSTEM
    system(command);
}

Patched Code (Hypothetical):

void execute_command(char *command, int user_id) {
    // Validate user privileges before execution
    if (!is_privileged(user_id)) {
        log_error("Unauthorized command execution attempt");
        return;
    }
    // Drop privileges to a lower level if needed
    set_effective_uid(LOW_PRIV_USER);
    system(command);
}

The patch likely adds privilege validation and context switching to ensure that commands are executed with the appropriate user context, preventing low-privileged users from escalating.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Access to a managed system with a low-privileged user account.
• Network connectivity to the KACE agent (default port 443 or 8080).
• Knowledge of the agent's API or command protocol.

Exploitation Steps:

1. Reconnaissance: Identify the KACE agent version and listening service.

   nmap -sV -p 443,8080 <target_ip>
   

2. Craft Malicious Payload: Create a request that triggers privilege escalation.

   import socket
   payload = b"EXECUTE_CMD: whoami > /tmp/priv_esc.txt"
   s = socket.socket()
   s.connect(("target_ip", 443))
   s.send(payload)
   s.close()
   

3. Execute: Run the script to execute a command with elevated privileges.
4. Verify: Check for the output file or use a reverse shell.

Note: No public exploit code is available; this is a conceptual example.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual agent communication patterns (e.g., unexpected commands).
• Enable logging on the KACE agent and central appliance.
• Use endpoint detection and response (EDR) to alert on privilege escalation attempts.

Defense:

• Apply patches immediately (upgrade to 14.0.97 or 14.1.19).
• Restrict network access to the agent service using firewalls.
• Implement least privilege principles on managed systems.
• Use application whitelisting to prevent unauthorized executables.

Indicators of Compromise (IOCs)

• Network: Unusual traffic to/from the KACE agent on ports 443 or 8080.
• Process: Unexpected processes running as SYSTEM or root spawned by the agent.
• File: Creation of files in sensitive directories (e.g., /tmp, C:\Windows\Temp) by the agent.
• Log: Agent logs showing unauthorized command execution attempts.
• Registry (Windows): Modifications to HKLM\SOFTWARE\Quest\KACE by non-admin users.

Detection Engineering

YARA Rule

rule CVE_2025_26850_KACE_PrivEsc {
    meta:
        description = "Detects potential exploitation of CVE-2025-26850 in Quest KACE SMA agent"
        author = "Valters IT"
        date = "2025-03-01"
        severity = "critical"
    strings:
        $s1 = "EXECUTE_CMD" ascii wide nocase
        $s2 = "PRIV_ESC" ascii wide nocase
        $s3 = "KACE_AGENT" ascii wide nocase
    condition:
        any of them
}

Sigma Rule

title: CVE-2025-26850 - Quest KACE SMA Agent Privilege Escalation
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects suspicious command execution via KACE agent
author: Valters IT
date: 2025/03/01
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: 'kace_agent.exe'
        CommandLine|contains: 'whoami'
    condition: selection
falsepositives:
    - Legitimate administrative tasks
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 443 (msg:"CVE-2025-26850 KACE Agent Privilege Escalation Attempt"; flow:to_server; content:"EXECUTE_CMD"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Patch: Upgrade all KACE SMA agents to version 14.0.97 or 14.1.19.
2. Isolate: If patching is not possible, isolate affected systems from the network.
3. Monitor: Increase monitoring for suspicious agent activity.

Long-Term Mitigations:

• Implement network segmentation to limit agent exposure.
• Use host-based firewalls to restrict agent communication to the KACE server only.
• Regularly audit agent configurations and logs.
• Apply the principle of least privilege to all managed systems.

Workarounds:

• Disable the agent service on non-critical systems temporarily.
• Use application control policies to block unauthorized command execution.

Valters IT