CVE-2023-27217 Overview
CVE-2023-27217 is a stack-based buffer overflow in the ChangeFriendlyName() function of the Belkin Smart Outlet V2 (F7c063) firmware version 2.00.11420.OWRT.PVT_SNSV2. A remote attacker can trigger the overflow by sending a crafted Universal Plug and Play (UPnP) request to the device. The flaw is categorized under CWE-787 (Out-of-bounds Write) and results in a Denial of Service (DoS) condition on the affected smart outlet. The vulnerability is reachable over the network without authentication or user interaction, making any exposed device a viable target.
Critical Impact
Unauthenticated attackers on the local network can crash the Belkin F7c063 smart outlet through a single crafted UPnP request, disabling automation and remote control of connected devices.
Affected Products
- Belkin Smart Outlet V2 (F7c063) hardware
- Belkin F7c063 firmware version 2.00.11420.OWRT.PVT_SNSV2
- Deployments exposing the UPnP service to untrusted network segments
Discovery Timeline
- 2023-05-18 - CVE-2023-27217 published to the National Vulnerability Database (NVD)
- 2025-01-22 - Last updated in the NVD database
Technical Details for CVE-2023-27217
Vulnerability Analysis
The Belkin F7c063 Smart Outlet exposes a UPnP service that processes device configuration requests over the network. The ChangeFriendlyName() handler accepts a user-supplied string used to update the device's display name. The handler copies that string into a fixed-size stack buffer without validating the input length against the destination size. A crafted UPnP request with an oversized FriendlyName value writes past the buffer boundary and corrupts adjacent stack memory, including saved return addresses.
The vulnerability is attacker-reachable from any host able to send SOAP messages to the device's UPnP endpoint. Successful exploitation causes the device process to crash, producing a Denial of Service. The Sternum IoT research team published the technical analysis describing the root cause and the affected request path. See the Sternum IoT Blog Vulnerability Analysis for additional details.
Root Cause
The root cause is the absence of bounds checking when the firmware copies attacker-controlled UPnP parameter data into a stack-allocated buffer inside ChangeFriendlyName(). The function relies on an unsafe string copy that trusts the caller-supplied length, which violates safe coding practices for handling external input on embedded devices.
Attack Vector
An attacker on the same network sends a SOAP-formatted UPnP request to the smart outlet's control endpoint. The request invokes the ChangeFriendlyName action with a FriendlyName argument longer than the destination buffer. The oversized payload overwrites the saved return address on the stack, causing the service to crash and the outlet to lose UPnP-driven control functionality. Exploitation requires no credentials and no user interaction.
No verified public proof-of-concept code is available. The vulnerability mechanism is described in prose only; refer to the Sternum IoT Blog Vulnerability Analysis for the request structure and offset details.
Detection Methods for CVE-2023-27217
Indicators of Compromise
- Unexpected restarts, reboots, or unresponsiveness of Belkin F7c063 smart outlets on the network.
- UPnP SOAPAction requests targeting ChangeFriendlyName with abnormally long string parameters.
- Loss of UPnP discovery responses (SSDP NOTIFY / M-SEARCH replies) from previously active F7c063 devices.
Detection Strategies
- Inspect HTTP traffic on UPnP control ports (typically TCP/49152–49154) for SOAP requests containing oversized FriendlyName values.
- Alert when intrusion detection signatures match UPnP ChangeFriendlyName actions with payloads exceeding expected length thresholds.
- Baseline normal UPnP request sizes for IoT devices and flag statistical outliers for review.
Monitoring Recommendations
- Forward IoT VLAN flow logs and packet metadata to a centralized analytics platform for retrospective hunting.
- Track availability of Belkin F7c063 devices using ICMP or application-layer health checks to surface DoS events quickly.
- Correlate device crash patterns with inbound UPnP traffic sources to identify attacker hosts.
How to Mitigate CVE-2023-27217
Immediate Actions Required
- Isolate Belkin F7c063 smart outlets on a dedicated IoT VLAN with no inbound access from untrusted hosts.
- Block external and guest network access to UPnP ports on the smart outlet to prevent crafted SOAP requests.
- Inventory affected devices running firmware 2.00.11420.OWRT.PVT_SNSV2 and prioritize them for replacement or firmware update review.
Patch Information
No vendor advisory or patched firmware build is listed in the NVD record or referenced vendor resources at the time of writing. Operators should consult Belkin support channels for firmware updates addressing the ChangeFriendlyName() handler and apply any released update as soon as it becomes available. Until a fix is published, treat the device as exposed and rely on network-layer controls.
Workarounds
- Disable UPnP control on the smart outlet where the feature is not required for operations.
- Restrict UPnP traffic at the router or switch using access control lists that allow only trusted management hosts.
- Replace unsupported or end-of-life F7c063 hardware with devices that receive active firmware maintenance.
# Example: block UPnP control traffic to the smart outlet at a Linux gateway
# Replace 192.0.2.25 with the IP of the Belkin F7c063 device
iptables -A FORWARD -d 192.0.2.25 -p tcp --dport 49152:49154 -j DROP
iptables -A FORWARD -d 192.0.2.25 -p udp --dport 1900 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
