CVE-2018-9487 in Android
Summary
by MITRE • 11/20/2024
In setVpnForcedLocked of Vpn.java, there is a possible blocking of internet traffic through vpn due to a bad uid check. This could lead to local denial of service with no additional execution privileges needed. User interaction is needed for exploitation.
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Analysis
by VulDB Data Team • 12/19/2024
The vulnerability identified as CVE-2018-9487 resides within the Android operating system's Vpn.java implementation, specifically in the setVpnForcedLocked method. This flaw represents a critical security weakness that could potentially disrupt network connectivity for users by improperly managing virtual private network traffic routing. The vulnerability stems from an inadequate uid validation mechanism that fails to properly verify the user identifier associated with network traffic, creating a pathway for malicious actors to manipulate VPN configurations.
The technical implementation flaw occurs when the system processes VPN traffic routing decisions based on insufficient user identification checks. This uid check failure allows for scenarios where network packets intended for legitimate applications may be incorrectly blocked or redirected through the VPN tunnel. The vulnerability operates at the system level where Android's network stack interacts with VPN services, creating a potential for unauthorized traffic manipulation that could render applications or services inaccessible. The flaw specifically affects how the system determines which applications should be forced through the VPN connection versus those that should bypass it.
From an operational perspective, this vulnerability creates a local denial of service condition that can severely impact user connectivity and application functionality. The attack requires only user interaction to be exploited, making it particularly dangerous as it can be triggered through seemingly benign actions such as opening malicious applications or navigating to compromised websites. Once exploited, the vulnerability can block internet traffic for specific applications or entire network sessions, effectively rendering them unusable without requiring any special privileges or root access. The impact extends beyond simple connectivity issues to potentially compromise the availability of critical services that depend on uninterrupted network access.
The vulnerability aligns with CWE-284, which addresses improper access control mechanisms, and demonstrates how weak authentication or authorization checks can lead to significant security consequences. From an ATT&CK framework perspective, this vulnerability maps to T1068, which covers 'Exploitation for Privilege Escalation', and T1499, covering 'Endpoint Denial of Service', as it enables attackers to create persistent denial of service conditions. The attack surface is particularly concerning as it operates within the system-level network management components, making it difficult to detect and mitigate through traditional application-level security measures.
Mitigation strategies should focus on implementing proper uid validation mechanisms that ensure only authorized applications can trigger VPN routing changes. System administrators should apply the latest security patches from Android vendors immediately upon availability, as this vulnerability affects multiple Android versions. Network monitoring should be enhanced to detect unusual traffic patterns that may indicate exploitation attempts. Additionally, users should be educated about the risks of interacting with untrusted applications and websites, as the vulnerability requires user interaction to be exploited. Organizations should implement network segmentation and monitoring solutions that can detect and alert on abnormal VPN traffic patterns that may indicate this vulnerability being exploited.