CVE-2018-20378 in Blue SDK
Summary
by MITRE
The L2CAP signaling channel implementation and SDP server implementation in OpenSynergy Blue SDK 3.2 through 6.0 allow remote, unauthenticated attackers to execute arbitrary code or cause a denial of service via malicious L2CAP configuration requests, in conjunction with crafted SDP communication over maliciously configured L2CAP channels. The attacker must have connectivity over the Bluetooth physical layer, and must be able to send raw L2CAP frames. This is related to L2Cap_HandleConfigReq in core/stack/l2cap/l2cap_sm.c and SdpServHandleServiceSearchAttribReq in core/stack/sdp/sdpserv.c.
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Analysis
by VulDB Data Team • 05/23/2020
The vulnerability identified as CVE-2018-20378 represents a critical security flaw within the OpenSynergy Blue SDK versions 3.2 through 6.0, specifically affecting the Layer 2 Control Access Protocol (L2CAP) signaling channel and Service Discovery Protocol (SDP) server implementations. This vulnerability stems from inadequate input validation and error handling mechanisms within the Bluetooth stack's core components, creating a pathway for remote attackers to compromise affected systems without requiring authentication. The flaw manifests through malicious L2CAP configuration requests that, when combined with crafted SDP communications, can be exploited to execute arbitrary code or induce denial of service conditions. The attack vector requires physical proximity to the target device since attackers must establish connectivity over the Bluetooth physical layer and send raw L2CAP frames, making this a significant concern for IoT devices and embedded systems that rely on Bluetooth connectivity. The technical implementation issues are rooted in the L2Cap_HandleConfigReq function located in core/stack/l2cap/l2cap_sm.c and the SdpServHandleServiceSearchAttribReq function within core/stack/sdp/sdpserv.c, which fail to properly validate incoming configuration parameters and service discovery requests respectively.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as successful exploitation can lead to complete system compromise through arbitrary code execution. Attackers leveraging this vulnerability can potentially gain unauthorized access to sensitive data, modify system configurations, or establish persistent backdoors within affected devices. The vulnerability affects a wide range of Bluetooth-enabled devices that utilize the OpenSynergy Blue SDK, including but not limited to wireless keyboards, mice, smart home devices, medical devices, and automotive systems. The combination of L2CAP configuration requests with malicious SDP communications creates a sophisticated attack chain that can bypass traditional network security controls since Bluetooth operates at the physical layer and often lacks the same security measures found in higher-level network protocols. This vulnerability particularly impacts environments where Bluetooth connectivity is prevalent and where devices are not properly segmented or monitored, as the attack can be executed without requiring any prior authentication or credentials.
Security professionals should consider this vulnerability in the context of the Common Weakness Enumeration framework, where it aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read vulnerabilities. The attack pattern follows the MITRE ATT&CK framework's technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute malicious commands on affected systems. Additionally, this vulnerability demonstrates characteristics of T1566, which involves the deployment of malicious payloads through social engineering or network-based attacks, particularly in IoT environments where physical security is often insufficient. Organizations should implement immediate mitigations including firmware updates to the latest versions of the OpenSynergy Blue SDK, network segmentation to isolate Bluetooth-enabled devices, and continuous monitoring for anomalous L2CAP and SDP traffic patterns. The vulnerability highlights the critical importance of proper input validation and error handling in embedded systems, particularly those operating at the Bluetooth stack level where low-level protocol implementations can have cascading security implications. Device manufacturers and system administrators should conduct comprehensive vulnerability assessments to identify all affected systems and implement appropriate security controls to prevent exploitation of this critical flaw.