CVE-2015-9157 in Android
Summary
by MITRE
In Android before 2018-04-05 or earlier security patch level on Qualcomm Snapdragon Mobile and Snapdragon Wear IPQ4019, MDM9206, MDM9607, MDM9625, MDM9635M, MSM8909W, SD 210/SD 212/SD 205, SD 400, SD 410/12, SD 600, SD 615/16/SD 415, SD 617, SD 650/52, SD 800, SD 808, and SD 810, in widevine_dash_cmd_handler(), rsp buffers are passed off to widevine commands. These rsp buffers have values in them, such as buffer lengths, that need to be validated to ensure that no buffer overflow/over-reads happen. However, rsp buffers are not always in locked memory, meaning a time-of-check, time-of-use issue can occur where we check that the value is valid, but then a race condition occurs where this memory is swapped out with a different, possibly out of range, value.
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Analysis
by VulDB Data Team • 01/26/2020
This vulnerability exists in Qualcomm Snapdragon mobile processors and wearable devices affected by Android security patches released before April 5, 2018. The issue resides in the widevine_dash_cmd_handler component which processes response buffers for widevine digital rights management operations. The flaw stems from improper validation of buffer length values within these response buffers, creating potential for buffer overflow or over-read conditions during command processing. This vulnerability specifically affects multiple Qualcomm chipsets including the SD 210/212/205, SD 400, SD 410/12, SD 600, SD 615/16/415, SD 617, SD 650/52, SD 800, SD 808, and SD 810 series processors.
The technical implementation of this vulnerability involves a time-of-check, time-of-use race condition scenario. During the processing of widevine commands, the system validates buffer parameters including lengths and other metadata values to ensure they fall within acceptable ranges. However, these validation checks occur before the actual buffer operations, while the response buffers themselves are not maintained in locked memory. This memory management approach creates a window where the buffer values can be modified between the validation phase and the execution phase, allowing malicious actors to exploit the race condition. The vulnerability is particularly concerning because it allows for potential memory corruption that could lead to arbitrary code execution within the secure environment.
The operational impact of this vulnerability extends beyond typical buffer overflow scenarios due to its location within the widevine DRM subsystem, which handles protected media content processing. Attackers could potentially exploit this vulnerability to execute arbitrary code with elevated privileges, potentially gaining access to encrypted media content or compromising the integrity of the secure element. The affected devices span a wide range of Qualcomm processors used in smartphones, tablets, and wearable devices, making this vulnerability particularly widespread. The vulnerability's classification aligns with CWE-367 Time-of-Check to Time-of-Use (TOCTOU) weakness, which specifically addresses race conditions occurring between validation and actual resource usage. This weakness is categorized under the broader ATT&CK technique T1059.007 for Command and Scripting Interpreter and potentially T1068 for Exploitation for Privilege Escalation.
Mitigation strategies for this vulnerability require immediate patching of affected Android devices through security updates from manufacturers. System administrators should ensure all devices are updated to security patches released after April 5, 2018, which address the memory management and buffer validation issues in the widevine component. Additionally, organizations should implement monitoring for suspicious behavior in media processing components and consider network segmentation to limit potential exploitation. The vulnerability highlights the importance of proper memory locking mechanisms in secure processing environments and demonstrates the critical need for comprehensive validation of buffer parameters in trusted execution environments. Device manufacturers should also consider implementing additional runtime checks and memory integrity verification to prevent similar race condition vulnerabilities in future implementations.