A critical security vulnerability discovered in popular Android rooting frameworks could allow malicious applications to completely compromise rooted devices, giving attackers full system control without user knowledge.
The vulnerability, first identified in KernelSU version 0.5.7, demonstrates how seemingly robust authentication mechanisms can be circumvented through clever exploitation techniques.
Rooting frameworks like KernelSU, APatch, SKRoot, and Magisk have gained widespread adoption among Android users seeking administrative privileges on their devices.
These tools operate by patching the Android kernel and hooking into critical system functions, creating communication channels between kernel space and user applications.
However, this deep system integration comes with significant security risks, particularly when authentication mechanisms fail to adequately verify the legitimacy of requesting applications.
The vulnerability exploits a fundamental weakness in how KernelSU authenticates manager applications.
When an application requests manager privileges through the prctl system call using the magic value 0xDEADBEEF, the framework performs three verification checks: validating the provided data directory path, confirming directory ownership, and verifying the APK’s digital signature.
While the first two checks are easily bypassed by any malicious application, the signature verification process contains a critical flaw that can be exploited.
Zimperium researchers identified that KernelSU’s signature verification relies on scanning the process’s file descriptor table for the first file matching the pattern /data/app/*/base.apk.
This approach assumes the discovered APK belongs to the requesting application, but attackers can manipulate file descriptor ordering to trick the system into validating the legitimate manager’s signature instead of their own malicious APK.
Advanced File Descriptor Manipulation Attack
The exploitation technique centers on sophisticated file descriptor manipulation that allows malicious applications to impersonate legitimate KernelSU managers.
Attackers accomplish this by bundling the official KernelSU manager APK within their malicious application and strategically opening it before making authentication requests to the kernel.
The attack sequence begins with the malicious application identifying its own base.apk file descriptor and locating a lower-numbered descriptor. If none exists, the attacker closes stdin (file descriptor 0) to create space.
The application then opens the bundled legitimate KernelSU manager APK, typically placed in the lib directory at a path like /data/app/. This path satisfies KernelSU’s filtering criteria while containing the authentic signature.
// Malicious authentication request
const char* data_path = "/data/data/com.attacker.manager";
int32_t result = -1;
prctl(KERNEL_SU_OPTION, CMD_BECOME_MANAGER, data_path, nullptr, &result);When KernelSU performs signature verification, it discovers the legitimate manager’s APK first in the file descriptor table and validates its signature, unknowingly granting manager privileges to the malicious application.
Once authenticated, the attacker gains access to powerful commands including CMD_GRANT_ROOT, CMD_ALLOW_SU, and CMD_SET_SEPOLICY, effectively achieving complete system compromise.
The vulnerability’s impact extends beyond individual devices to enterprise environments where rooted devices pose significant security risks.
Organizations using mobile device management solutions must implement comprehensive detection mechanisms to identify rooting tools and prevent potential exploitation of these critical vulnerabilities before they lead to data breaches or unauthorized system access.
Boost your SOC and help your team protect your business with free top-notch threat intelligence: Request TI Lookup Premium Trial.
Source link
