CVE-2019-2125 in Android
Summary
by MITRE
In ChangeDefaultDialerDialog.java, there is a possible escalation of privilege due to an overlay attack. This could lead to local escalation of privilege, granting privileges to a local app without the user's informed consent, with no additional privileges needed. User interaction is needed for exploitation. Product: Android. Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android-9. Android ID: A-132275252.
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Analysis
by VulDB Data Team • 08/01/2020
The vulnerability identified as CVE-2019-2125 represents a critical privilege escalation flaw within Android's system framework that exploits a overlay attack vector to compromise system security. This vulnerability specifically resides in the ChangeDefaultDialerDialog.java component, which is responsible for managing dialer application default settings within the Android operating system. The flaw allows malicious applications to potentially elevate their privileges without user consent, creating a significant security risk that affects multiple Android versions including 7.0, 7.1.1, 7.1.2, 8.0, 8.1, and 9.0. The vulnerability operates through a sophisticated overlay attack mechanism that manipulates the system's default dialer selection process to gain unauthorized access to elevated privileges.
The technical implementation of this vulnerability stems from insufficient input validation and privilege checking within the dialer dialog component. When a user interacts with the default dialer selection interface, the system fails to properly verify the authenticity and authorization level of the requesting application. This creates an opportunity for malicious applications to spoof legitimate system dialogs or manipulate the overlay layer to present false interfaces that trick the system into granting elevated privileges. The vulnerability specifically targets the Android framework's trust model, where the system assumes that applications requesting default dialer status are legitimate, without proper verification of their actual privileges or intentions. This flaw falls under the CWE-284 access control weakness category, specifically addressing improper access control mechanisms that allow unauthorized privilege escalation.
The operational impact of CVE-2019-2125 extends beyond simple privilege elevation to create a comprehensive security compromise that can enable further attacks and data exfiltration. An attacker exploiting this vulnerability can gain access to sensitive system functions, potentially accessing user data, making unauthorized calls, monitoring communications, or even installing additional malicious software. The local escalation of privilege means that once an attacker successfully exploits this vulnerability, they can operate with system-level privileges without requiring additional authentication or user interaction for subsequent attacks. The requirement for user interaction to initiate the exploit does not mitigate the overall risk since the attack can be disguised as legitimate system operations, making it particularly dangerous in real-world scenarios where users might be unaware of the compromise until significant damage has occurred. This vulnerability aligns with ATT&CK technique T1068 privilege escalation through local system exploitation, where adversaries leverage system-level flaws to gain elevated access.
Mitigation strategies for CVE-2019-2125 require a multi-layered approach combining system-level patches, user awareness, and application security controls. Google addressed this vulnerability through Android security updates that strengthened the validation mechanisms within the dialer selection dialog and implemented additional checks to prevent unauthorized privilege escalation through overlay attacks. Organizations should ensure all affected Android devices receive the latest security patches and updates, particularly focusing on the specific versions mentioned in the vulnerability report. System administrators should implement application whitelisting policies to restrict which applications can request default dialer status, and users should exercise caution when installing applications that request system-level permissions. The vulnerability highlights the importance of proper overlay security controls and demonstrates how seemingly benign system components can be exploited to create significant security risks. Regular security audits and monitoring of system privileges should be implemented to detect potential exploitation attempts, while security frameworks should be updated to address similar overlay attack patterns that may exist in other system components.