CVE-2020-11202: Qualcomm Qcm6125 Buffer Overflow Vulnerability

CVE-2020-11202 Overview

CVE-2020-11202 is a buffer overflow/underflow vulnerability in Qualcomm Snapdragon chipsets affecting the DSP (Digital Signal Processor) component. The vulnerability occurs when typecasting a buffer passed by the CPU internally in the library, where the buffer is not aligned with the actual size of the expected structure. This memory corruption vulnerability affects a wide range of Qualcomm Snapdragon platforms including Auto, Compute, Consumer IOT, Industrial IOT, and Mobile product lines.

This vulnerability is part of a broader set of DSP security issues discovered by Check Point Research, collectively known as "Achilles." Exploitation of this vulnerability could allow a local attacker with low privileges to achieve code execution, information disclosure, or denial of service on affected devices.

Critical Impact

Local attackers can exploit this buffer overflow to potentially execute arbitrary code, escalate privileges, or cause system instability on billions of Android devices powered by affected Qualcomm Snapdragon chipsets.

Affected Products

• Qualcomm Snapdragon Auto (SA6145P, SA6155, SA6155P, SA8155, SA8155P)
• Qualcomm Snapdragon Mobile (SDM640, SDM670, SDM710, SDM830, SDM845, SM6125, SM6150, SM7125, SM7150, SM8150)
• Qualcomm Snapdragon Compute/IOT (QCM6125, QCS410, QCS603, QCS605, QCS610, QCS6125)
• Qualcomm Modem Platforms (SDX50M, SDX55, SDX55M)

Discovery Timeline

• November 12, 2020 - CVE-2020-11202 published to NVD
• November 2020 - Qualcomm releases security patch via November 2020 Security Bulletin
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-11202

Vulnerability Analysis

This vulnerability resides in the Hexagon DSP component of Qualcomm Snapdragon chipsets. The DSP is a specialized processor that handles compute-intensive tasks such as audio/video processing, machine learning inference, and sensor data processing. The vulnerability manifests when the DSP library receives a buffer from the CPU and performs a typecast operation without properly validating that the buffer size matches the expected structure size.

The memory corruption can result in either a buffer overflow (writing beyond allocated memory) or buffer underflow (accessing memory before the buffer start), depending on the size mismatch between the passed buffer and the target structure. This type of vulnerability (CWE-787: Out-of-bounds Write) can lead to serious security consequences including arbitrary code execution within the DSP context.

Root Cause

The root cause is improper size validation during buffer typecasting operations in the DSP library. When the CPU passes a buffer to the DSP for processing, the library code performs a typecast to interpret the buffer as a specific data structure. However, the code fails to verify that the actual buffer size matches the expected structure size before performing operations on the data.

This size misalignment creates a condition where memory operations (reads or writes) can exceed the buffer boundaries, corrupting adjacent memory regions or reading sensitive data from unintended memory locations.

Attack Vector

The attack vector requires local access to the device with low-privilege user permissions. An attacker could exploit this vulnerability through:

1. Malicious Application: A specially crafted Android application that interacts with the DSP through the exposed APIs, passing malformed buffers designed to trigger the overflow condition.

2. DSP Service Manipulation: Sending crafted requests to system services that relay data to the DSP, exploiting the size mismatch in the typecasting operation.

3. Privilege Escalation Chain: Using this vulnerability as part of a larger attack chain to escalate privileges from a sandboxed application to higher privilege levels on the device.

For detailed technical analysis of Qualcomm DSP vulnerabilities and exploitation techniques, refer to the Check Point Achilles Research and their Pwn2Own Qualcomm DSP Analysis.

Detection Methods for CVE-2020-11202

Indicators of Compromise

• Unusual DSP-related crashes or system instability on affected Snapdragon devices
• Suspicious applications requesting access to DSP-related APIs or services
• Memory corruption signatures in kernel logs related to Hexagon DSP operations
• Unexpected behavior in audio, video, or sensor processing subsystems

Detection Strategies

• Monitor for applications attempting to interact with low-level DSP interfaces or proprietary Qualcomm services
• Implement behavioral analysis to detect anomalous memory access patterns in DSP-related processes
• Deploy endpoint detection solutions capable of monitoring firmware-level activities on mobile devices
• Review application permissions for unusual requests related to hardware acceleration or DSP access

Monitoring Recommendations

• Enable detailed logging for DSP-related system services and kernel modules
• Monitor system stability metrics for unexplained crashes in multimedia or AI processing components
• Track firmware versions across device fleets to ensure vulnerable firmware is identified
• Implement mobile threat defense solutions with vulnerability assessment capabilities

How to Mitigate CVE-2020-11202

Immediate Actions Required

• Apply the November 2020 Qualcomm security patches to all affected devices immediately
• Audit deployed devices to identify those running vulnerable Snapdragon firmware versions
• Restrict installation of applications from untrusted sources on affected devices
• Consider network-level controls to limit exposure of devices pending firmware updates

Patch Information

Qualcomm addressed this vulnerability in their November 2020 Security Bulletin. The fix implements proper size validation before typecasting buffers in the affected DSP library code.

For Android devices, the patch is delivered through OEM firmware updates. Organizations should coordinate with device manufacturers to obtain and deploy the updated firmware. Enterprise mobility management (EMM) solutions can help track firmware versions and enforce update compliance.

Workarounds

• Implement strict application whitelisting to prevent execution of potentially malicious applications
• Use mobile device management (MDM) solutions to enforce security policies on affected devices
• Limit device exposure by restricting access to sensitive networks until patches are applied
• Monitor for and block applications exhibiting suspicious DSP interaction patterns

# Check Android device Snapdragon chipset and firmware version
adb shell getprop ro.board.platform
adb shell getprop ro.build.fingerprint
adb shell getprop ro.vendor.build.security_patch