CVE-2023-28577: Qualcomm Fastconnect Use-After-Free Flaw

CVE-2023-28577 Overview

CVE-2023-28577 is a Use-After-Free (UAF) vulnerability affecting Qualcomm firmware across numerous chipsets, including the Snapdragon 8 Gen 1, Snapdragon 865/870 5G series, FastConnect WiFi/Bluetooth modules, and various audio codecs. The vulnerability exists in the Camera Request Manager subsystem, specifically in the CAM_REQ_MGR_RELEASE_BUF function call handling. Due to missing validation checks, a race condition can occur where one thread unmaps kernel virtual addresses while another thread is actively using them, leading to a use-after-free condition that can be exploited for local privilege escalation.

Critical Impact

This UAF vulnerability allows a local attacker with low privileges to potentially achieve arbitrary code execution in kernel context, leading to complete device compromise on affected Qualcomm-powered Android devices, IoT devices, and wearables.

Affected Products

• Qualcomm Snapdragon 8 Gen 1 Firmware
• Qualcomm Snapdragon 865/865+/870 5G Firmware
• Qualcomm FastConnect 6800/6900/7800 Firmware
• Qualcomm QCA6391/QCA6426/QCA6436 Firmware
• Qualcomm WCN3660B/WCN3680B/WCN3950/WCN3980/WCN3988 Firmware
• Qualcomm Snapdragon X55 5G/XR2 5G Firmware
• Qualcomm SW5100/SW5100P Wearable Firmware
• Qualcomm WCD9341/WCD9370/WCD9380 Audio Codec Firmware
• Qualcomm WSA8810/WSA8815/WSA8830/WSA8835 Speaker Amplifier Firmware

Discovery Timeline

• August 8, 2023 - CVE-2023-28577 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-28577

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a memory corruption vulnerability that occurs when a program continues to use a pointer after the memory it references has been freed or unmapped. In CVE-2023-28577, the flaw resides within Qualcomm's Camera Request Manager kernel driver, which manages buffer operations for camera functionality on Android devices.

The core issue stems from insufficient synchronization in the CAM_REQ_MGR_RELEASE_BUF ioctl handler. When processing buffer release requests, the driver fails to verify whether the target buffer is currently in use by another thread. This creates a dangerous race condition window where concurrent operations can lead to memory corruption.

The vulnerability requires local access to the device and a malicious application with permissions to interact with the camera subsystem. While the attack requires low privileges, successful exploitation could allow an attacker to escalate privileges to kernel level, potentially bypassing Android security boundaries and gaining full device control.

Root Cause

The root cause of CVE-2023-28577 is the absence of a proper reference counting or locking mechanism in the CAM_REQ_MGR_RELEASE_BUF function path. When the cam_mem_get_cpu_buf() function retrieves a kernel virtual address for a buffer, no atomic check is performed to ensure the buffer will remain valid throughout its usage. This allows a concurrent thread to invoke CAM_REQ_MGR_RELEASE_BUF and unmap the kernel virtual address while it is still being accessed, resulting in a dangling pointer that references freed memory.

Attack Vector

The attack vector is local, requiring the attacker to have code execution capability on the target device. A malicious application or compromised process can exploit this vulnerability through the following mechanism:

1. The attacker application opens the camera device and requests buffer allocation through the Camera Request Manager interface
2. One thread calls cam_mem_get_cpu_buf() to obtain a kernel virtual address for an allocated buffer
3. While the first thread is actively using the buffer, a second thread issues a CAM_REQ_MGR_RELEASE_BUF ioctl to release the same buffer
4. The kernel unmaps the virtual address, but the first thread continues to hold and use the now-invalid pointer
5. Depending on heap state and timing, this UAF condition can be leveraged for arbitrary read/write in kernel memory, potentially leading to privilege escalation

The exploitation requires precise timing and heap manipulation techniques commonly used in Android kernel exploits. Due to the race condition nature, exploitation reliability may vary, but sophisticated attackers can achieve consistent results through heap spraying and other memory manipulation techniques.

Detection Methods for CVE-2023-28577

Indicators of Compromise

• Unexpected crashes or kernel panics related to camera subsystem operations
• Anomalous memory access patterns in kernel logs referencing cam_mem or cam_req_mgr functions
• Applications requesting camera permissions exhibiting suspicious concurrent buffer operations
• Kernel oops messages indicating use-after-free conditions in camera driver modules

Detection Strategies

• Monitor for applications making rapid or unusual sequences of camera ioctl calls, particularly CAM_REQ_MGR_RELEASE_BUF operations
• Implement kernel address sanitizer (KASAN) during development and testing to detect UAF conditions
• Deploy endpoint detection solutions capable of monitoring kernel-level memory operations and identifying anomalous patterns
• Review application permissions and audit processes with camera access for suspicious behavior

Monitoring Recommendations

• Enable verbose kernel logging for camera driver operations to capture potential exploitation attempts
• Monitor system stability metrics for unexplained crashes in camera-related kernel modules
• Implement runtime integrity monitoring to detect privilege escalation attempts following memory corruption
• Track firmware versions across device fleet to ensure timely identification of vulnerable systems

How to Mitigate CVE-2023-28577

Immediate Actions Required

• Apply the Qualcomm security patch referenced in the August 2023 Security Bulletin immediately
• Update device firmware through OEM channels to receive the patched camera driver
• Audit installed applications and remove any untrusted apps with camera permissions
• For enterprise environments, enforce mobile device management (MDM) policies requiring current security patches

Patch Information

Qualcomm has addressed this vulnerability in their August 2023 Security Bulletin. Device manufacturers should integrate the patched firmware and distribute updates to end users through their standard update channels. End users should check for system updates from their device manufacturer and apply available security patches.

Organizations managing fleets of Qualcomm-powered devices should prioritize firmware updates for devices running affected chipsets, particularly those in sensitive environments where local privilege escalation could have significant security implications.

Workarounds

• Restrict camera permissions to only essential trusted applications through device settings or MDM policies
• Consider disabling camera functionality entirely on high-security devices until patches can be applied
• Implement application whitelisting to prevent untrusted code from executing on vulnerable devices
• Enable SELinux in enforcing mode to limit the impact of potential exploitation

# Verify current firmware version (Android device example)
adb shell getprop ro.build.fingerprint
adb shell getprop ro.board.platform

# Check for Qualcomm chipset and security patch level
adb shell getprop ro.build.version.security_patch

# Review camera permissions for installed apps
adb shell dumpsys package | grep -A 5 "android.permission.CAMERA"