CVE-2023-21492

What is Samsung Mobile Device Log File Management?

Samsung Android devices maintain diagnostic and debug log files as part of their modified Android OS layer (One UI). These log files are written by the kernel, framework, and system services to record device state, crash diagnostics, and debugging information. In certain Samsung-specific configurations, kernel-level code inadvertently writes sensitive information — specifically, kernel memory pointer values — to log files that are accessible to system-privileged processes. Kernel pointer values provide ASLR (Address Space Layout Randomization) bypass information: knowing the address of a kernel object reveals the base address of the kernel's memory layout, enabling subsequent memory corruption exploits to target specific kernel structures precisely.

Overview

CVE-2023-21492 is an information disclosure vulnerability (CWE-532 — Insertion of Sensitive Information into Log File) in Samsung mobile devices running Android 11, 12, and 13. Kernel memory pointer addresses are written to device log files, and a privileged local attacker can read these log files to obtain kernel ASLR layout information. This enables a bypass of ASLR as a prerequisite for kernel privilege escalation exploits. Samsung patched CVE-2023-21492 in the May 2023 security update. CISA added it to the KEV catalog on May 19, 2023 — 15 days after publication, confirming active exploitation in the wild.

Affected Versions

Technical Details

Insertion of sensitive information into log files (CWE-532) occurs when a system component writes security-sensitive data — in this case, kernel memory addresses (pointers) — to log storage that can be read by attacker-controlled processes. The exploitation chain:

1. Exploit initial access — the attacker achieves some level of code execution on the Samsung device (e.g., via a browser exploit or malicious app installation)
2. Read log files — using elevated (but not fully root) system privileges, the attacker reads device log files (e.g., via logcat with system-level access, or by reading directly from /proc/kmsg or device-specific log paths)
3. Extract kernel pointer values — parse the log output to find Samsung-specific log entries that contain kernel memory addresses (e.g., printed as %p hex values in debug statements that were not removed from production builds)
4. Defeat ASLR — use the extracted kernel addresses to calculate the base address of the kernel image and key kernel data structures, enabling a subsequent kernel write vulnerability to be exploited with precise targeting

The PR:H (high privilege required) constraint reflects that the attacker needs elevated system-level access to read the log files containing kernel pointers — but this is consistent with the kind of limited privilege level an attacker might have after exploiting an app sandbox escape.

Discovery

CVE-2023-21492 was patched in Samsung's May 2023 SMR. The rapid 15-day CISA KEV addition suggests exploitation was already known at or shortly before disclosure — likely through forensic analysis of a compromised Samsung device where the exploit chain's ASLR-bypass stage was identified.

Exploitation Context

Samsung devices running Android 11–13 represent a significant portion of enterprise and government Android deployments. Kernel ASLR bypass information leaks like CVE-2023-21492 are exploited as intermediate steps in multi-stage Android exploit chains:

• An attacker with limited app sandbox code execution uses the ASLR leak to learn kernel memory layout
• Armed with kernel addresses, a kernel write vulnerability (heap overflow, UAF, etc.) can be reliably exploited to gain root or kernel code execution
• Full kernel compromise enables disabling Android security controls, accessing credential stores, and deploying persistent implants

The combination of CVE-2023-21492 with a kernel write primitive provides a reliable kernel exploitation path on unpatched Samsung devices.

Remediation

1. Apply the Samsung May 2023 security update — patches CVE-2023-21492; verify the device security patch level is May 2023 or later (Settings → About phone → Software information → Android security patch level).
2. Keep Samsung devices current with monthly security updates — Samsung releases monthly SMRs that address new vulnerabilities; maintaining current patch levels minimizes the kernel exploitation attack surface.
3. Apply Mobile Device Management (MDM) policies — enforce minimum Android security patch level requirements for enrolled Samsung devices; quarantine or restrict access for non-compliant devices.
4. Replace unsupported Samsung devices — Samsung devices past their end of security support (typically 4-5 years after release for flagship models) will not receive patches; replace them with devices receiving current updates.