CVE-2023-48423: Google Android RCE Vulnerability

CVE-2023-48423 Overview

CVE-2023-48423 is a critical out-of-bounds write vulnerability in the dhcp4_SetPDNAddress function within dhcp4_Main.c of the Android operating system. This vulnerability arises from a missing bounds check, allowing attackers to write data beyond the allocated buffer boundaries. The flaw enables remote code execution without requiring any user interaction or additional execution privileges, making it particularly dangerous in network-facing scenarios.

Critical Impact

Remote attackers can achieve arbitrary code execution on vulnerable Android devices through network-based attacks targeting the DHCP client implementation, without requiring user interaction or elevated privileges.

Affected Products

• Google Android (all versions prior to December 2023 security patch)
• Google Pixel devices (addressed in December 2023 Pixel security bulletin)
• Android devices using the vulnerable DHCP implementation

Discovery Timeline

• 2023-12-08 - CVE-2023-48423 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-48423

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), a memory corruption flaw that occurs when data is written beyond the boundaries of an allocated memory buffer. In the context of CVE-2023-48423, the dhcp4_SetPDNAddress function fails to properly validate the size of input data before copying it into a fixed-size buffer.

The DHCP (Dynamic Host Configuration Protocol) client implementation is responsible for handling network configuration responses from DHCP servers. When processing PDN (Packet Data Network) address information, the vulnerable function does not verify that the incoming data fits within the allocated buffer space, allowing malicious DHCP responses to corrupt adjacent memory regions.

Root Cause

The root cause is a missing bounds check in the dhcp4_SetPDNAddress function within dhcp4_Main.c. When the function receives PDN address data from a DHCP response, it copies this data into a buffer without first verifying that the data length does not exceed the buffer's capacity. This allows an attacker controlling a rogue DHCP server or performing a man-in-the-middle attack on the network to send specially crafted DHCP responses containing oversized PDN address fields.

Attack Vector

The attack is network-based and requires no user interaction. An attacker can exploit this vulnerability through the following attack scenarios:

The attacker positions themselves on the same network segment as the target device, either by compromising existing network infrastructure or by setting up a rogue access point. When the victim's Android device requests DHCP configuration, the attacker responds with a malicious DHCP packet containing an oversized PDN address field. The vulnerable dhcp4_SetPDNAddress function processes this response and writes the malicious data beyond the buffer boundary, potentially overwriting critical memory structures such as function pointers or return addresses. This memory corruption can be leveraged to achieve arbitrary code execution in the context of the DHCP client process.

Detection Methods for CVE-2023-48423

Indicators of Compromise

• Unusual DHCP traffic patterns with oversized or malformed PDN address fields in DHCP responses
• Unexpected crashes or abnormal behavior of network-related processes on Android devices
• Anomalous network activity from Android devices following DHCP exchanges
• Memory corruption errors or segmentation faults in system logs related to DHCP processing

Detection Strategies

• Deploy network intrusion detection systems (NIDS) to monitor for malformed DHCP packets with abnormally large option fields
• Implement endpoint detection and response (EDR) solutions capable of detecting memory corruption attacks on Android devices
• Monitor system logs for crashes in DHCP-related processes or components
• Use network traffic analysis to identify suspicious DHCP server responses that deviate from expected patterns

Monitoring Recommendations

• Enable verbose logging for network stack components on managed Android devices
• Configure network monitoring tools to alert on DHCP traffic anomalies
• Implement application crash monitoring to detect potential exploitation attempts
• Review network infrastructure logs for unauthorized DHCP server activity

How to Mitigate CVE-2023-48423

Immediate Actions Required

• Apply the December 2023 Android security patch immediately to all affected devices
• Ensure devices are connected only to trusted networks until patches can be applied
• Review network infrastructure for any signs of rogue DHCP servers
• Implement network segmentation to limit exposure of unpatched devices

Patch Information

Google addressed this vulnerability in the Android Security Bulletin December 2023. Device manufacturers and carriers should ensure this security update is deployed to all affected devices. Users should verify their devices have received the December 2023 security patch level or later by checking Settings > About Phone > Android Security Patch Level.

Workarounds

• Use static IP configuration instead of DHCP on critical devices until patches are applied
• Implement 802.1X network access control to prevent rogue DHCP server attacks
• Deploy DHCP snooping on network switches to filter malicious DHCP responses
• Consider network isolation for unpatched devices to reduce exposure to potential attacks

Organizations should prioritize patching as workarounds do not fully address the underlying vulnerability and only reduce the attack surface.