CVE-2019-17532 in Wemo Switch 28B
Summary
by MITRE
An issue was discovered on Belkin Wemo Switch 28B WW_2.00.11057.PVT-OWRT-SNS devices. They allow remote attackers to cause a denial of service (persistent rules-processing outage) via a crafted ruleDbBody element in a StoreRules request to the upnp/control/rules1 URI, because database corruption occurs.
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Analysis
by VulDB Data Team • 01/08/2024
The vulnerability identified as CVE-2019-17532 affects Belkin Wemo Switch devices running firmware version 28B WW_2.00.11057.PVT-OWRT-SNS and potentially other models within the Wemo ecosystem. This issue represents a critical security flaw that enables remote attackers to disrupt device functionality through a specific manipulation of the device's rule processing system. The vulnerability exists within the Universal Plug and Play (UPnP) implementation of these smart home devices, specifically targeting the rules1 control URI endpoint where device rules are managed and stored.
The technical exploitation of this vulnerability occurs through a carefully crafted ruleDbBody element within a StoreRules request sent to the upnp/control/rules1 URI. When the device receives this malformed input, it processes the data without proper validation or sanitization, leading to database corruption that results in persistent rule processing outages. This flaw demonstrates a classic buffer overflow or input validation vulnerability where the system fails to properly validate user-supplied data before processing it within the database context. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, though the specific implementation appears to involve database corruption rather than traditional memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service, as it can render the affected Wemo Switch devices completely non-functional for rule-based operations. This persistent outage affects users' ability to manage their smart home automation workflows, potentially disabling scheduled lighting, security alerts, or other automated functions that depend on the device's rule processing capabilities. The vulnerability affects the core functionality of these devices, which are designed to provide seamless integration into home automation ecosystems, making this particularly concerning for users who rely on these devices for routine home management tasks.
From an attacker perspective, this vulnerability represents a low-effort, high-impact vector for disrupting smart home environments. The remote nature of the attack means that adversaries can exploit this flaw from anywhere on the internet without requiring physical access or local network presence. The persistent nature of the outage suggests that once exploited, the device requires manual intervention or firmware reflash to restore normal operation, making it particularly disruptive for users who depend on continuous automation services. This vulnerability aligns with ATT&CK technique T1499.001 for network denial of service and demonstrates how IoT devices can become persistent points of failure in larger security infrastructures.
Mitigation strategies for this vulnerability should include immediate firmware updates from Belkin, which would address the input validation issues in the rule processing system. Network segmentation and firewall rules can help limit exposure by blocking unauthorized access to the upnp/control/rules1 endpoint, though this approach may impact legitimate device functionality. Users should also implement network monitoring to detect unusual rule processing activity that might indicate exploitation attempts. The vulnerability highlights the importance of proper input validation and database integrity checks in IoT device firmware, particularly for systems that process user-defined rules or configurations. Organizations should consider implementing device authentication and authorization mechanisms to prevent unauthorized rule modifications, as well as regular security assessments of their IoT device inventory to identify similar vulnerabilities across their smart home or enterprise IoT deployments.