CVE-2021-41850 in Simo
Summary
by MITRE • 03/12/2022
An issue was discovered in Luna Simo PPR1.180610.011/202001031830. A pre-installed app with a package name of com.skyroam.silverhelper writes three IMEI values to system properties at system startup. The system property values can be obtained via getprop by all third-party applications co-located on the device, even those with no permissions granted, exposing the IMEI values to processes without enforcing any access control.
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Analysis
by VulDB Data Team • 03/16/2022
This vulnerability exists within the Luna Simo PPR1.180610.011/202001031830 firmware version where a pre-installed application named com.skyroam.silverhelper performs an improper privilege escalation by writing sensitive IMEI identifiers to system properties during device boot. The flaw stems from the application's ability to modify system-level properties without proper access controls or permission checks, creating a critical security weakness that violates fundamental security principles of least privilege and access control enforcement. The vulnerability manifests as an insecure system property modification that allows any third-party application to access these values through the standard getprop command, regardless of the application's permission level or security context.
The technical implementation of this vulnerability involves the pre-installed application leveraging its system-level privileges to write three distinct IMEI values to Android system properties during the device startup sequence. These system properties are then accessible through the getprop command which is designed for system administration purposes but lacks proper access control mechanisms to prevent unauthorized access by unprivileged applications. The flaw represents a classic case of improper access control where system properties that should be protected are made globally readable, effectively creating a information disclosure vulnerability that exposes device identifiers to all applications on the device.
From an operational security perspective, this vulnerability creates significant risks for device users and organizations relying on device security. The exposure of IMEI values through system properties provides attackers with persistent device identifiers that can be used for tracking, profiling, or device-specific attacks. The vulnerability impacts all third-party applications on the device regardless of their permission level, meaning even applications with minimal privileges can obtain these identifiers. This creates a persistent threat vector that can be exploited by malicious applications to correlate user activities across different applications, track device ownership, or target specific devices for further attacks. The vulnerability also violates the principle of least privilege by allowing unrestricted access to sensitive device identifiers.
The impact of this vulnerability aligns with CWE-284 Access Control Issues and can be mapped to ATT&CK technique T1069.001 Local Network Permissions. This weakness enables adversaries to gather device identifiers that can be used for various malicious purposes including device fingerprinting, tracking user behavior across applications, and potentially facilitating more sophisticated attacks such as device-specific malware or targeted phishing campaigns. The vulnerability is particularly concerning because it affects the core system properties mechanism and operates at a level that bypasses normal Android permission models, making it difficult for users or security applications to detect or prevent the information disclosure.
Mitigation strategies should focus on implementing proper access control enforcement for system properties and restricting write access to system-level identifiers. Device manufacturers should ensure that sensitive system properties are not accessible through standard getprop commands without proper authentication or authorization mechanisms. Security measures should include implementing proper privilege separation where system properties containing sensitive information are restricted to specific system-level processes or require specific permissions to access. Additionally, regular security audits should verify that no pre-installed applications are writing sensitive identifiers to system properties without proper access controls, and that existing system properties are properly secured against unauthorized access attempts. The vulnerability highlights the importance of secure system property management and proper privilege enforcement in mobile device security implementations.