Sierra Wireless AirLink ES450 Gateway upload.cgi Arbitrary File Upload and Remote Code Execution (RCE) Vulnerability (CVE-2018-4063)
Executive & SecOps Summary
SECOPS ASSESSMENTSierra Wireless AirLink ES450 firmware version 4.9.3 and its ACEManager web interface
An authenticated attacker can upload arbitrary executable files via a crafted HTTP POST request, leading to remote code execution with system privileges
Apply the latest official firmware security patches and restrict external internet access to the ACEManager interface
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
According to Sierra Wireless security advisories, administrators must upgrade the gateway firmware to the latest secure release. This can be performed via the ACEManager UI or the command-line interface.
# Example CLI commands to download and flash the latest secure firmware
# 1. Download the latest secure firmware image
wget https://source.sierrawireless.com/resources/airlink/software_downloads/es450/es450-firmware-latest.bin
# 2. Apply the firmware upgrade via the Sierra CLI tool
sierra-cli --target 192.168.1.1 --user admin --pass 'YOUR_PASSWORD' --upgrade es450-firmware-latest.bin2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict access to the ACEManager interface (default port 9191) by implementing firewall rules to allow only trusted administrator IP addresses.
# Block external access to ACEManager port and allow only a trusted admin IP (e.g., 10.10.10.50)
iptables -A INPUT -p tcp --dport 9191 -j DROP
iptables -I INPUT -s 10.10.10.50 -p tcp --dport 9191 -j ACCEPT3. Log Audit & IoC Verification Commands
Inspect web server logs for suspicious POST requests targeting upload.cgi and scan the web root for unauthorized executable files.
# Search web server access logs for upload.cgi activity
grep -i 'upload.cgi' /var/log/lighttpd/access.log /var/log/httpd/access_log 2>/dev/null
# Scan the web root directory for recently modified executable scripts (.sh, .cgi, .php)
find /www/ /usr/share/www/ -type f -mtime -30 \( -name '*.sh' -o -name '*.cgi' -o -name '*.php' \)Block Exploits Instantly with Managed Virtual Patching Rules
Can't patch production immediately? Deploy managed WAF rules at the edge to intercept RCE, SQLi, and deserialization payloads before they hit your origin server.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2018-4063) is an unrestricted file upload flaw (CWE-434) residing within the upload.cgi functionality of the ACEManager web interface on Sierra Wireless AirLink ES450 gateways. The root cause is the lack of proper validation on file extensions and execution permissions of uploaded files, allowing an attacker to place executable scripts or binaries directly into the web server's document root or executable paths.
2. Exploitation Mechanics & Attack Scenario
To exploit this vulnerability, an attacker must first establish an authenticated session with ACEManager. Once authenticated, the attacker sends a specially crafted HTTP POST request containing multipart/form-data to the upload.cgi endpoint. The payload includes an executable script or binary targeted at a directory accessible by the web server. After the file is successfully uploaded, the attacker requests the file's URL directly, triggering execution and granting them an interactive shell on the gateway.
3. Infrastructure & Business Impact
Sierra Wireless AirLink ES450 gateways are widely deployed in industrial IoT, M2M, and enterprise networking environments. Because this vulnerability is actively exploited and listed in the CISA KEV catalog, it poses a severe threat. Successful exploitation allows complete compromise of the gateway, enabling attackers to perform lateral movement into internal Industrial Control Systems (ICS) networks, sniff network traffic, conduct Man-in-the-Middle (MitM) attacks, and disrupt critical business operations.
Official Vendor Advisories & References
An exploitable remote code execution vulnerability exists in the upload.cgi functionality of Sierra Wireless AirLink ES450 FW 4.9.3. A specially crafted HTTP request can upload a file, resulting in executable code being uploaded, and routable, to the webserver. An attacker can make an authenticated HTTP request to trigger this vulnerability.
Frequently Asked SecOps Questions (CVE-2018-4063)
FAQQ1. How critical is CVE-2018-4063 and is it actively exploited in the wild?
CVE-2018-4063 is rated CVSS 8.8 (HIGH) with a 30-day EPSS exploitation probability of 27.3%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2018-4063?
Primary impacted vendors include sierra wireless across airlink es450. Scope summary: Sierra Wireless AirLink ES450 firmware version 4.9.3 (specifically the upload.cgi component in ACEManager)
Q3. What temporary mitigations or workarounds exist for CVE-2018-4063 before patching?
[Mitigation] Apply the latest official firmware security patches and restrict external internet access to the ACEManager interface Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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