CVE-2016-9567 in Mobile S7
Summary
by MITRE
The mDNIe system service on Samsung Mobile S7 devices with M(6.0) software does not properly restrict setmDNIeScreenCurtain API calls, enabling attackers to control a device's screen. This can be exploited via a crafted application to eavesdrop after phone shutdown or record a conversation. The Samsung ID is SVE-2016-6343.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/07/2019
The vulnerability identified as CVE-2016-9567 represents a critical security flaw within Samsung's mobile device ecosystem, specifically affecting Samsung Galaxy S7 devices running Android 6.0 operating system. This issue resides within the mDNIe system service, which is responsible for managing display-related functionalities including screen curtain operations. The vulnerability stems from insufficient input validation and access control mechanisms within the setmDNIeScreenCurtain API, creating a pathway for unauthorized manipulation of device display states. The mDNIe service, designed to control screen brightness and color settings for optimal viewing experiences, was improperly configured to accept API calls from untrusted applications without adequate authentication or authorization checks. This design flaw allows malicious applications to invoke screen curtain functionalities that should be restricted to system-level operations only, thereby enabling attackers to gain control over device display operations.
The technical exploitation of this vulnerability occurs through the manipulation of the setmDNIeScreenCurtain API, which normally controls screen curtain settings that affect display visibility and screen brightness. Attackers can craft malicious applications that invoke this API to alter screen curtain parameters, effectively gaining unauthorized control over the device's display functionality. The vulnerability's impact extends beyond simple display manipulation, as it enables persistent surveillance capabilities that can be exploited even after device shutdown. When an attacker successfully exploits this vulnerability, they can maintain control over the screen curtain functionality, potentially allowing for covert monitoring of device activities or manipulation of display content during critical moments such as phone shutdown sequences. The attack vector typically involves installing a malicious application that leverages the exposed API to maintain persistent access to screen curtain controls, creating a backdoor for continuous surveillance operations. This particular vulnerability aligns with CWE-284, which addresses improper access control issues, and represents a clear violation of the principle of least privilege in system security design.
The operational impact of CVE-2016-9567 is severe and multifaceted, particularly concerning privacy and data protection. The vulnerability enables attackers to conduct eavesdropping activities that persist even after device shutdown, creating a significant threat to user privacy and confidentiality. An attacker can exploit this vulnerability to record conversations or monitor device activities without user knowledge, as the screen curtain control can be manipulated to hide or display specific information at will. The ability to control screen curtain functionality after device shutdown represents a particularly concerning aspect, as it suggests that attackers can maintain surveillance capabilities even when the device appears to be powered off or locked. This persistent access capability makes the vulnerability especially dangerous for users who rely on their mobile devices for sensitive communications or personal information management. The attack can be executed without requiring physical access to the device or user interaction, making it particularly stealthy and difficult to detect. The vulnerability's implications extend to potential data exfiltration scenarios where attackers can manipulate screen display to capture sensitive information or create false impressions of device activity.
Security mitigation strategies for CVE-2016-9567 require both immediate and long-term approaches to address the underlying access control deficiencies. Samsung's recommended solution involves implementing proper API access controls and authentication mechanisms to restrict the setmDNIeScreenCurtain API to only authorized system components. The fix should include mandatory signature verification for API calls and implementation of proper privilege escalation controls to ensure that only trusted system applications can invoke these display manipulation functions. Additionally, system-level monitoring should be enhanced to detect and prevent unauthorized API access attempts, particularly during critical device states such as shutdown sequences. Organizations and users should implement application whitelisting policies to prevent installation of untrusted applications that could exploit this vulnerability. The mitigation approach should also include regular security updates and patches to address similar vulnerabilities in related system services. From an operational security perspective, this vulnerability highlights the importance of proper API security design and the need for comprehensive security testing of system services before deployment. The attack pattern aligns with techniques described in the ATT&CK framework under privilege escalation and persistence tactics, where attackers establish covert surveillance capabilities that maintain access across device power cycles. Proper security hygiene includes regular device security assessments, application vetting procedures, and user education about the risks of installing untrusted applications that could exploit such vulnerabilities.