CVE-2017-6520 in Soundtouch
Summary
by MITRE
The Multicast DNS (mDNS) responder used in BOSE Soundtouch 30 inadvertently responds to IPv4 unicast queries with source addresses that are not link-local, which allows remote attackers to cause a denial of service (traffic amplification) or obtain potentially sensitive information via port-5353 UDP packets.
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Analysis
by VulDB Data Team • 09/22/2020
The vulnerability identified as CVE-2017-6520 affects the Multicast DNS responder implementation within BOSE Soundtouch 30 devices, representing a critical security flaw in network discovery protocols. This issue stems from improper handling of IPv4 unicast queries that originate from non-link-local source addresses, creating a fundamental breach in the mDNS protocol's intended operational boundaries. The affected device fails to properly validate query source addresses before responding, which fundamentally undermines the security model designed to prevent unauthorized network discovery operations.
The technical flaw manifests when the mDNS responder processes UDP packets sent to port 5353, the standard port for mDNS traffic. Under normal circumstances, mDNS queries should only be accepted from link-local addresses to prevent cross-network interference and maintain network integrity. However, the Soundtouch 30 device responds to unicast queries regardless of their source address, allowing remote attackers to exploit this behavior for malicious purposes. This deviation from standard mDNS protocol implementation creates a pathway for attackers to manipulate the device's network behavior through crafted UDP packets.
The operational impact of this vulnerability extends beyond simple denial of service conditions, creating potential information disclosure risks that align with attack patterns described in the ATT&CK framework under network infiltration and reconnaissance techniques. Remote attackers can leverage this flaw to amplify network traffic by sending small queries that generate disproportionately large responses, creating traffic amplification effects that can overwhelm network resources and potentially disrupt legitimate device operations. The vulnerability's exploitation capabilities also enable attackers to gather potentially sensitive information about the device's network configuration and operational status.
From a cybersecurity perspective, this vulnerability represents a failure in protocol validation that directly relates to CWE-20, which describes improper input validation in software systems. The lack of proper source address validation in the mDNS responder creates a persistent security gap that could be exploited by threat actors to perform reconnaissance activities, establish persistent network presence, or conduct larger-scale attacks against connected networks. The vulnerability's impact is particularly concerning given that the affected device operates in consumer environments where network security awareness may be limited.
Mitigation strategies for CVE-2017-6520 should focus on implementing proper network segmentation to isolate affected devices from critical network segments, deploying network access controls to restrict UDP port 5353 traffic, and applying firmware updates when available from BOSE. Network administrators should also consider implementing intrusion detection systems to monitor for anomalous mDNS traffic patterns and establish logging procedures to track potential exploitation attempts. The vulnerability highlights the importance of proper protocol implementation in embedded devices and serves as a reminder of the security implications that arise when standard network protocols are not properly enforced in consumer-grade IoT devices.