CVE-2018-8076 in ZenMate
Summary
by MITRE
ZenMate 1.5.4 for macOS suffers from a type confusion vulnerability within the com.zenmate.chron-xpc LaunchDaemon component. The LaunchDaemon implements an XPC service that uses an insecure XPC API for accessing data from an inbound XPC message. This could potentially result in an XPC object of the wrong type being passed as the first argument to the xpc_connection_create_from_endpoint function if controlled by an attacker. In recent versions of macOS and OS X, Apple has implemented an internal check to prevent such XPC API abuse from occurring, thus making this vulnerability only result in a denial of service if exploited by an attacker.
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Analysis
by VulDB Data Team • 01/13/2020
The vulnerability identified as CVE-2018-8076 represents a type confusion issue within the ZenMate 1.5.4 macOS extension, specifically within the com.zenmate.chron-xpc LaunchDaemon component. This flaw exists in the XPC service implementation that handles inter-process communication between the extension and system components. The vulnerability stems from improper handling of XPC message data where the LaunchDaemon fails to properly validate the type of objects received through XPC communication channels. The insecure XPC API usage creates a scenario where attacker-controlled data can influence the type of object passed to critical system functions, potentially leading to unpredictable behavior within the XPC framework.
The technical exploitation of this vulnerability occurs through manipulation of XPC messages sent to the vulnerable LaunchDaemon service. When an attacker crafts malicious XPC messages with specifically crafted data types, they can cause the system to interpret objects incorrectly during the xpc_connection_create_from_endpoint function call. This type confusion manifests as the system receiving an XPC object of an unexpected type, which can lead to memory corruption or system instability. The vulnerability is particularly concerning because it operates at a low system level within the XPC communication framework, which is fundamental to macOS inter-process communication mechanisms. The flaw essentially allows an attacker to manipulate the object type passed to a critical API function, potentially enabling arbitrary code execution or system compromise.
From an operational impact perspective, this vulnerability creates a significant security risk for macOS systems running the affected ZenMate extension. The type confusion vulnerability can be leveraged by attackers to perform denial of service attacks against the system, effectively preventing legitimate users from accessing system resources or services. While the vulnerability may not directly enable arbitrary code execution in recent macOS versions due to built-in protections, it still represents a serious threat to system availability and stability. The exploitability of this issue is enhanced by the fact that it operates within the privileged LaunchDaemon context, potentially allowing attackers to gain elevated privileges or disrupt system operations. The vulnerability affects the core XPC service infrastructure, making it particularly dangerous as it can impact multiple system components that rely on proper XPC communication.
The mitigation strategies for CVE-2018-8076 should focus on immediate remediation through software updates from the vendor, as the vulnerability exists in a specific version of the ZenMate extension. Users should disable or uninstall the affected extension until a patched version is available. System administrators should monitor for any unusual XPC service behavior or denial of service incidents that may indicate exploitation attempts. Network monitoring tools can be configured to detect anomalous XPC communication patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-457, which describes the use of uninitialized variables, and can be categorized under ATT&CK technique T1059.007 for XPC communication abuse. Organizations should implement comprehensive patch management policies to ensure all system components, particularly those handling inter-process communication, are regularly updated with security patches. Additionally, system hardening measures including XPC service access controls and monitoring of LaunchDaemon activities can help reduce the attack surface and detect potential exploitation attempts.