Remote Exploit Uncovered in Viasat Satellite Modems via Hidden Web Interface
A newly uncovered security weakness—tracked as CVE-2024-6198—has put a range of Viasat satellite modems at serious risk, enabling remote attackers to seize control without any login credentials. The vulnerability stems from a stack buffer overflow buried within a little-known component called SNORE, part of the modem’s embedded web interface.
Rated 7.7 (High) under the CVSS v4 framework, the flaw spans several modem variants including RM4100, RM4200, EM4100, RM5110, RM5111, RG1000, RG1100, EG1000, and EG1020.
The issue came to light thanks to an in-depth automated firmware audit by ONEKEY Research Lab, shedding light on the broader dangers posed by opaque, hard-to-inspect firmware running in vital communications gear.
These modems operate a trimmed-down web server (lighttpd) exposed on TCP ports 3030 and 9882, intended for remote system management—but instead opening the door to code execution if exploited.
Inside the Exploit: How a Flawed CGI Script in Viasat Modems Opens the Door to Full System Takeover
The root of this vulnerability lies in a poorly handled HTTP request parser embedded within the index.cgi executable housed at /usr/local/SNORE. This binary mishandles incoming web requests—specifically GET, POST, and DELETE—by using a reckless sscanf call that blindly copies data from the REQUEST_URI environment variable into memory without enforcing boundary checks.
By crafting a URI payload such as:
http://192.168.100.1:9882/snore/blackboxes/AAAAAAAA…[512+ bytes]
an attacker can flood a fixed-length stack buffer, corrupting the call stack and steering execution flow via the overwritten program counter.
Although the stack is marked non-executable, exploitation is still achievable through Return-Oriented Programming (ROP). This technique chains together legitimate code snippets already present in the binary to assemble a functional payload—effectively weaponizing the modem’s own instructions to execute arbitrary commands.
The vulnerability carries a CVSS v4.0 score of 7.7 (High) with the vector:
AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H. This combination means that no user interaction or privileges are needed, and the attack can be launched by anyone on the same local network—even without authentication.
If successfully exploited, the attacker gains root-level access to the modem’s internals. From there, they could intercept satellite-bound traffic, extract stored credentials, manipulate configurations, or even implant stealthy malware in remote or high-security environments where Viasat devices serve as critical communication nodes.
Threat Profile Overview
| Category | Description |
|---|---|
| Impacted Devices | Viasat modem families including: RM4100, RM4200, EM4100 (firmware < 3.8.0.4); RM5110, RM5111, RG1000, RG1100, EG1000, EG1020 (firmware ≤ 4.3.0.1) |
| Threat Vector | Full remote code execution through exploitable buffer overflow in SNORE’s web control logic |
| Attack Conditions | Requires attacker access to the same local network; no authentication necessary |
| Severity Rating | CVSS v4.0: 7.7 (High) — indicates significant risk in LAN-accessible environments |
Firmware at Risk & Remediation Timeline
The security flaw impacts multiple generations of Viasat satellite modems, specifically:
- RM4100, RM4200, EM4100 units running firmware prior to version 3.8.0.4
- RM5110, RM5111, RG1000, RG1100, EG1000, and EG1020 devices on firmware 4.3.0.1 or earlier
To close the security gap, Viasat has issued firmware updates:
- 3.8.0.4 for RM4100-series modems
- 4.3.0.2 for all later models
These fixes are being pushed via over-the-air (OTA) distribution; however, devices must be online and reachable to receive and install updates. Admins are urged to confirm patch levels through device management panels.
Recommended Defensive Measures
While patches roll out, organizations should take immediate containment steps:
- Disconnect vulnerable devices from untrusted or internet-exposed networks
- Monitor system logs for suspicious URI activity targeting ports 3030 and 9882
- Enforce VLANs or firewall policies to isolate SNORE interfaces from lateral threats
Bigger Picture: Satellite Tech in the Crosshairs
The broader implications go well beyond this single CVE. As Viasat hardware becomes deeply embedded in critical infrastructure sectors—including defense, offshore operations, and energy grids—firmware-level attack surfaces demand continuous scrutiny.
This incident reinforces an urgent need for:
- Stronger exploit hardening (e.g., stack canaries, Control-Flow Integrity)
- End-to-end firmware transparency
- Automated threat monitoring at the supply chain level
With attackers increasingly leveraging Return-Oriented Programming (ROP) against IoT-class systems, the line between software flaw and operational compromise is thinner than ever.
