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CVE-2018-4063 Sierra Wireless AirLink ALEOS Remote Code Execution

Sierra Wireless

Remote Code Execution
Unrestricted File Upload
Active Exploitation

Overview

This incident centers on CVE-2018-4063, a vulnerability in Sierra Wireless AirLink ALEOS router firmware's web management interface (upload.cgi) that allows authenticated attackers to upload arbitrary files that become executable on the device. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added it to its Known Exploited Vulnerabilities catalog after reports of active exploitation in the wild.

The vulnerability affects routers commonly used in Operational Technology (OT) / Industrial networks, including utilities, transportation, and enterprise edge devices.

Technical Specifications

Attribute Details
CVE ID CVE-2018-4063
Vulnerability Type Unrestricted File Upload with Dangerous Type (CWE-434)
Affected Product Sierra Wireless AirLink ALEOS
Affected Models ES450 and related models
Affected Component ACEManager's upload.cgi
CVSS 3.1 Score 8.8 (HIGH)
Attack Vector Network
Exploitation Status Active exploitation confirmed - Added to CISA KEV
Affected Sectors Operational Technology (OT), Industrial networks, utilities, transportation

Technical Details

Vulnerability Classification

  • Vulnerability: Unrestricted file upload with dangerous type (CWE-434)
  • Affects Sierra Wireless AirLink ALEOS router firmware

Affected Component

  • ACEManager's upload.cgi in Sierra Wireless AirLink ALEOS firmware
  • Examples: ES450 and related models

Exploitation Mechanism

  • An authenticated attacker sends a crafted HTTP request to upload a file
  • Can overwrite existing executable scripts on the device
  • Because the management service runs as root, this leads to arbitrary code execution with elevated privileges

Root Cause

  • Improper validation of uploaded file types
  • Lack of restrictions on file placement/execution
  • Privileged execution context (root)

Attack Scenario

1. Prerequisite: Credential Acquisition

Attacker obtains or guesses valid credentials for the web interface via:

  • Credential theft
  • Default passwords
  • Brute force attacks
  • Phishing

2. Exploit Delivery

Attacker sends a crafted HTTP request to the router's /cgi-bin/upload.cgi endpoint

3. Payload Upload

  • A malicious executable or script is uploaded into a system directory
  • Potentially replacing an existing file with executable permissions

4. Execution

  • The router executes the malicious file under root
  • Giving the attacker full control of the device

5. Post-Exploit Objectives

The attacker can:

  • Persist on the network
  • Pivot deeper into the internal network
  • Deploy botnets or crypto-miners
  • Intercept or manipulate communications
  • Disrupt services depending on the device's operational role

Impact Assessment

  • Compromise of routers/edge devices with root privileges
  • Full control over device configuration and operation
  • Ability to execute arbitrary commands
  • Potential lateral movement into enterprise or industrial networks
  • Access to internal network segments
  • Pivot point for further attacks
  • Service interruption or manipulation of connectivity
  • Network traffic interception or tampering
  • Denial of service capabilities
  • Increased risk in Operational Technology environments:
    • Utilities
    • Transportation
    • Manufacturing
    • Critical infrastructure
  • Potential impact on industrial control systems
  • Impact on Federal Civilian Executive Branch (FCEB) systems under U.S. directives
  • Must be patched or replaced per CISA requirements

Mitigations

🔄 Apply Vendor Firmware Updates

  • Upgrade to the latest ALEOS versions where CVE-2018-4063 is patched
  • This is the primary mitigation
  • Check Sierra Wireless security advisories for patch availability

🚫 Isolate or Decommission

  • Isolate or decommission affected devices if updates are not available
  • Remove from production networks
  • Replace with patched or alternative hardware

🔐 Credential Management

  • Change default/weak credentials immediately
  • Enforce strong password policies:
    • Minimum length requirements
    • Complexity requirements
    • Regular password rotation
  • Implement multi-factor authentication (MFA) if supported

🔒 Access Control

Restrict access to management interfaces:

  • Deploy behind firewalls
  • Require VPN access for management
  • Implement network segmentation
  • Whitelist authorized IP addresses only
  • Disable remote management if not required

📊 Monitoring & Detection

  • Monitor for exploit attempts in logs and IDS/IPS alerts
  • Look for:
    • Unusual file uploads to /cgi-bin/upload.cgi
    • Unexpected authentication attempts
    • New processes spawning from web services
    • Unusual outbound connections
    • File modifications in system directories

🏗️ Network Segmentation

  • Network segmentation to limit exposure of routers to untrusted networks
  • Isolate OT/ICS networks from corporate networks
  • Place routers in DMZ or protected network segments
  • Limit inter-segment communication

🔍 Incident Response

If exploitation is suspected:

File System Audit

  • Check for unexpected files in system directories
  • Look for recently modified executables
  • Review file permissions and ownership

Process Analysis

  • Monitor for unusual processes running as root
  • Check for unexpected network connections
  • Analyze running services

Log Review

  • Review web server access logs for suspicious uploads
  • Check authentication logs for brute force attempts
  • Analyze system logs for privilege escalation

Network Analysis

  • Monitor for unusual outbound connections
  • Check for command and control (C2) traffic
  • Analyze network traffic patterns

Resources & References

Official Advisories & CISA

Vulnerability Details & Analysis

Active Exploitation

This vulnerability is being actively exploited in the wild and has been added to CISA's Known Exploited Vulnerabilities (KEV) catalog.

Organizations using Sierra Wireless AirLink ALEOS routers must: - Patch immediately to latest firmware - Isolate or decommission devices if patching is not possible - Review access controls and credentials - Monitor for indicators of compromise

OT/ICS Considerations

This vulnerability affects devices commonly deployed in Operational Technology (OT) and Industrial Control Systems (ICS) environments. Organizations in critical infrastructure sectors should:

  • Prioritize patching or isolation of these devices
  • Implement network segmentation between IT and OT
  • Monitor for anomalous behavior in OT networks
  • Coordinate with ICS/SCADA security teams