CVE-2025-26693

Executive Summary

CVE-2025-26693 is a local information disclosure vulnerability in OpenHarmony versions 5.0.3 and prior. The flaw allows a local attacker to leak sensitive information by abusing the get permission API. With a CVSS score of 3.3 (Low), the risk is limited to local access scenarios, but it could expose internal system data or user credentials. No public exploit code or proof-of-concept is available, and no patch has been released. The vulnerability is classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) and aligns with MITRE ATT&CK tactic TA0007 (Discovery).

Supply Chain & Package Security

OpenHarmony is an open-source operating system for IoT and embedded devices. This vulnerability affects the core permission management component, which is distributed as part of the OS image. No package manager (NPM, PyPI, Go, Ruby) is involved, but the risk extends to any device running the affected versions.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
• Base Score: 3.3 (Low)
• Attack Vector: Local (AV:L) – requires physical or shell access to the device.
• Attack Complexity: Low (AC:L) – no special conditions needed.
• Privileges Required: Low (PR:L) – attacker needs a low-privileged account.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – impact stays within the vulnerable component.
• Confidentiality Impact: Low (C:L) – limited information disclosure.
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: Low. Exploitation requires local access, and the impact is limited to information leakage. However, in IoT environments, local access may be easier to obtain (e.g., via USB or debug interfaces).

Deep Dive & Mechanics

The vulnerability resides in the permission management subsystem of OpenHarmony. The get permission API, intended to query permission status for applications, fails to properly validate the caller’s identity or the sensitivity of the requested permission data. A local attacker with low privileges can invoke this API to enumerate permissions granted to other applications or system services, potentially revealing:

• Installed application list
• Permission assignments (e.g., camera, microphone, location)
• System service capabilities

The root cause is insufficient access control on the API endpoint. The system does not enforce that the caller has the right to view permissions of other entities, leading to an information leak.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code path is speculative based on typical permission API implementations.

Vulnerable Code (Conceptual):

// In permission_manager.c
int get_permission(const char *target_app, const char *permission) {
    // No check on caller's identity
    PermissionEntry *entry = lookup_permission(target_app, permission);
    if (entry) {
        return entry->granted; // Leaks permission status
    }
    return -1;
}

Patched Code (Hypothetical):

// In permission_manager.c
int get_permission(const char *target_app, const char *permission, uid_t caller_uid) {
    // Verify caller has permission to query target
    if (!is_authorized(caller_uid, target_app)) {
        return -EPERM;
    }
    PermissionEntry *entry = lookup_permission(target_app, permission);
    if (entry) {
        return entry->granted;
    }
    return -1;
}

The patch would add an authorization check to ensure the caller is allowed to query the target application’s permissions.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Local shell access on an OpenHarmony device (version ≤ 5.0.3)
• Low-privileged user account (e.g., shell or u0_aXXX)

Exploitation Steps:

1. Connect to the device via ADB or SSH.
2. Use the hidumper or custom C code to call the vulnerable API.
3. Enumerate permissions of system apps to discover sensitive capabilities.

Example Command (using hidumper):

# Query permissions of a system app
hidumper --permission com.example.systemapp

Custom C Exploit (Conceptual):

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    // Simulate calling the vulnerable API
    // In real scenario, use IPC to permission manager
    printf("Enumerating permissions...\n");
    // Loop through known app UIDs
    for (int uid = 1000; uid < 2000; uid++) {
        char cmd[256];
        snprintf(cmd, sizeof(cmd), "hidumper --permission --uid %d", uid);
        system(cmd);
    }
    return 0;
}

Blue Team

Detection:

• Monitor for repeated calls to hidumper with --permission flag.
• Look for unusual patterns in permission query logs.
• Use auditd to track access to permission manager IPC endpoints.

Hunting:

• Search for processes with high frequency of get_permission syscalls.
• Correlate with low-privileged user accounts.

Prevention:

• Restrict ADB/SSH access to authorized users only.
• Apply principle of least privilege to all user accounts.
• Monitor for unauthorized physical access to devices.

Indicators of Compromise (IOCs)

• File Hashes: None available (no exploit code).
• Process Names: hidumper (when used with --permission flag).
• Log Entries:
  • Repeated permission query attempts from same UID.
  • get_permission API calls with unusual target UIDs.
• Network: No network indicators (local vulnerability).
• Behavioral: Sudden increase in permission enumeration activity.

Detection Engineering

YARA Rule

rule CVE_2025_26693_Permission_Leak {
    meta:
        description = "Detects exploitation attempts of CVE-2025-26693 via hidumper permission queries"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-26693"
    strings:
        $hidumper = "hidumper" nocase
        $permission_flag = "--permission" nocase
        $uid_flag = "--uid" nocase
    condition:
        $hidumper and $permission_flag and $uid_flag
}

Sigma Rule

title: CVE-2025-26693 Permission Enumeration via hidumper
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects repeated use of hidumper with --permission flag, indicating possible exploitation of CVE-2025-26693
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/hidumper'
        CommandLine|contains|all:
            - '--permission'
            - '--uid'
    condition: selection
falsepositives:
    - Legitimate system administration
level: medium

Suricata Rule

alert ip any any -> any any (msg:"CVE-2025-26693 - OpenHarmony Permission Enumeration Attempt"; content:"hidumper"; content:"--permission"; content:"--uid"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict local access to OpenHarmony devices (disable ADB, SSH, and debug interfaces).
2. Monitor logs for suspicious permission query activity.
3. Apply the principle of least privilege to all user accounts.

Long-Term Fix:

• Await an official patch from OpenHarmony.
• In the interim, consider applying a custom patch to the permission manager to add authorization checks (as shown in the patched code section).

Workarounds:

• Disable the get_permission API for non-privileged users via SELinux policies.
• Use AppArmor or similar to restrict access to the permission manager IPC.

Valters IT