CVE-2018-5891 in Snapdragon Mobile
Summary
by MITRE
While processing modem SSR after IMS is registered, the IMS data daemon is restarted but the ipc_dataHandle is no longer available. Consequently, the DPL thread frees the internal memory for dataDHandle but the local variable pointer is not updated which can lead to a Use After Free condition in Snapdragon Mobile and Snapdragon Wear.
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Analysis
by VulDB Data Team • 05/03/2020
The vulnerability described in CVE-2018-5891 represents a critical memory management flaw within the Qualcomm Snapdragon mobile and wearable platforms that affects the IMS (IP Multimedia Subsystem) data handling mechanisms. This issue specifically manifests during the modem SSR (System Software Reset) process when IMS is already registered, creating a scenario where the IMS data daemon undergoes a restart while maintaining inconsistent state management between different system components. The root cause lies in the improper handling of inter-process communication data structures, particularly the ipc_dataHandle variable that serves as a critical communication channel between the IMS data daemon and the DPL (Data Processing Layer) thread.
The technical implementation of this vulnerability stems from a fundamental flaw in memory deallocation protocols where the DPL thread correctly identifies that the internal memory associated with dataDHandle should be freed, yet fails to update the local variable pointer reference accordingly. This creates a dangerous scenario where the memory location is deallocated and potentially reused by other processes while maintaining an active reference to the freed memory address. The condition constitutes a classic use-after-free vulnerability as defined by CWE-416, where a program continues to reference memory after it has been freed, leading to unpredictable behavior and potential exploitation. The vulnerability impacts the Snapdragon Mobile and Snapdragon Wear platforms, indicating a hardware-level software stack issue that affects device stability and security.
The operational impact of this vulnerability extends beyond simple system instability, potentially enabling malicious actors to execute arbitrary code or cause denial of service conditions on affected devices. When the DPL thread attempts to access the freed memory location through the unchanged pointer reference, it may inadvertently access data that has been overwritten by subsequent memory allocations, leading to data corruption, system crashes, or in more severe cases, privilege escalation attacks. The vulnerability's exploitation potential is heightened by its occurrence during normal system operation, specifically during modem reset procedures that are routine in mobile environments, making it particularly concerning for mobile device security. This type of vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation, as it provides a foundation for further exploitation within the mobile platform's security model.
Mitigation strategies for this vulnerability require both immediate patching of the affected Qualcomm Snapdragon firmware components and implementation of robust memory management practices within the affected software stack. Device manufacturers should prioritize rolling out firmware updates that correct the memory deallocation logic and ensure proper pointer management during the IMS data daemon restart process. Additionally, system-level protections such as address space layout randomization and memory protection mechanisms should be enabled to reduce exploitation success rates. The vulnerability highlights the importance of proper resource management in embedded systems and the need for comprehensive testing of state transition scenarios, particularly during system reset and recovery operations. Security teams should monitor for signs of exploitation attempts targeting this specific memory management flaw while maintaining awareness of the broader implications for mobile platform security and the potential for similar issues in related subsystems.