CVE-2025-24493

Executive Summary

CVE-2025-24493 is a local information disclosure vulnerability in OpenHarmony, an open-source operating system for IoT and edge devices. The flaw, caused by a race condition (CWE-362), allows a local attacker with low privileges to leak sensitive information. The vulnerability affects OpenHarmony v5.0.3 and all prior versions. With a CVSS score of 5.5 (Medium), the attack requires local access and high attack complexity, but no user interaction. No public exploit code or patch details are currently available. The EPSS score of 0.0% indicates a very low probability of exploitation in the wild at this time.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a core operating system issue in OpenHarmony.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
• Base Score: 5.5 (Medium)
• Attack Vector (AV): Local (L) – The attacker must have physical or shell access to the device.
• Attack Complexity (AC): High (H) – Exploitation requires precise timing due to the race condition.
• Privileges Required (PR): Low (L) – The attacker needs a low-privileged account.
• User Interaction (UI): None (N) – No victim action is required.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): High (H) – Sensitive data can be fully disclosed.
• Integrity (I): None (N) – No data modification is possible.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. The requirement for local access and high complexity reduces the immediate risk, but the potential for information leakage in IoT/edge environments is significant.

Deep Dive & Mechanics

The vulnerability is a classic race condition (CWE-362) in OpenHarmony's kernel or a privileged service. A race condition occurs when the behavior of a system depends on the timing or interleaving of multiple threads or processes. In this case, a local attacker can exploit a window between a security check and the actual use of a resource (TOCTOU - Time of Check, Time of Use).

Hypothetical Attack Flow:

1. A low-privileged process requests access to a protected resource (e.g., a file, memory region, or IPC channel).
2. The kernel performs a security check (e.g., verifying the process's UID/GID).
3. Before the resource is actually accessed, the attacker's process rapidly modifies the state (e.g., changes a symlink, modifies memory mappings, or sends a signal).
4. The kernel then uses the modified state to access the resource, bypassing the original security check.
5. The attacker gains read access to sensitive data (e.g., kernel memory, other processes' data, or configuration files).

The specific vulnerable component in OpenHarmony is not publicly identified, but common targets for such race conditions include:

• File system operations (e.g., /proc, /sys entries)
• Inter-process communication (IPC) mechanisms
• Memory management (e.g., mmap, mprotect)
• Device driver interfaces

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical vulnerable and patched code example is provided.

Vulnerable Code (C pseudocode):

int access_privileged_file(char *path, int uid) {
    // Time of Check
    if (check_permissions(path, uid) != 0) {
        return -EPERM;
    }
    // Race window: attacker can change 'path' here
    // Time of Use
    int fd = open(path, O_RDONLY);
    if (fd < 0) {
        return -EACCES;
    }
    // Read and return data
    return read_and_return(fd);
}

Patched Code (C pseudocode):

int access_privileged_file(char *path, int uid) {
    // Use a single atomic operation
    int fd = open(path, O_RDONLY | O_NOFOLLOW);
    if (fd < 0) {
        return -EACCES;
    }
    // Check permissions on the opened file descriptor
    if (check_permissions_fd(fd, uid) != 0) {
        close(fd);
        return -EPERM;
    }
    // Read and return data
    return read_and_return(fd);
}

The patched version eliminates the race window by opening the file first and then checking permissions on the file descriptor, preventing symlink attacks or path changes.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Local shell access to an OpenHarmony device (v5.0.3 or earlier).
• Low-privileged user account.

Exploitation Steps (Hypothetical):

1. Identify a vulnerable race condition target (e.g., a file in /proc or a device node).
2. Create a script that continuously attempts to access the target while another thread modifies the state.
3. Use a loop to increase the probability of winning the race.

Example Exploit Script (Bash):

#!/bin/bash
# Hypothetical exploit for CVE-2025-24493
# Requires two terminals

# Terminal 1: Attacker modifies the target
while true; do
    ln -sf /etc/shadow /tmp/vuln_link
    ln -sf /dev/null /tmp/vuln_link
done

# Terminal 2: Attacker reads the target
while true; do
    cat /tmp/vuln_link 2>/dev/null
done

Note: This is a simplified example. Real exploitation would require precise timing and knowledge of the specific vulnerable component.

Blue Team (Detection & Defense)

Detection:

• Monitor for high-frequency file operations on /tmp or other writable directories.
• Alert on unusual patterns of symlink creation and deletion.
• Use kernel auditing (e.g., auditd) to track race condition attempts.

Defense:

• Apply the vendor patch when available.
• Restrict local access to trusted users only.
• Enable SELinux or AppArmor to confine processes.
• Use kernel hardening features like symlink and hardlink restrictions.

Indicators of Compromise (IOCs)

• File System Anomalies:
  • Rapid creation and deletion of symlinks in /tmp or /dev/shm.
  • Unexpected access to /proc or /sys entries by low-privileged processes.
• Process Behavior:
  • High CPU usage from processes performing repetitive file operations.
  • Multiple processes racing to access the same resource.
• Log Entries:
  • Kernel messages indicating permission errors or race condition warnings.
  • Audit logs showing open system calls with O_NOFOLLOW flag missing.

Detection Engineering

YARA Rule

rule CVE_2025_24493_Race_Condition {
    meta:
        description = "Detects potential race condition exploitation for CVE-2025-24493"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "unknown"
    strings:
        $s1 = "ln -sf" ascii wide
        $s2 = "/tmp/" ascii wide
        $s3 = "while true" ascii wide
    condition:
        all of ($s1, $s2, $s3) and filesize < 10KB
}

Sigma Rule

title: CVE-2025-24493 Race Condition Exploitation Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects rapid symlink creation/deletion patterns indicative of race condition exploitation
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/ln'
        CommandLine|contains: '-sf'
    condition: selection
    timeframe: 5s
    aggregation:
        - field: CommandLine
          method: count
          condition: gt 100
falsepositives:
    - Legitimate build scripts
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-24493 Potential Data Exfiltration"; flow:to_server,established; content:"|0d 0a|"; within:100; classtype:attempted-recon; sid:1000001; rev:1;)

Note: The Suricata rule is a placeholder for network-based detection. Since this is a local vulnerability, network detection is less relevant.

Remediation & Mitigation

Immediate Actions:

1. Restrict Local Access: Limit shell access to trusted administrators only.
2. Monitor Systems: Implement the detection rules above to identify exploitation attempts.
3. Apply Kernel Hardening: Enable fs.protected_symlinks and fs.protected_hardlinks sysctl settings.

Long-Term Fix:

• Apply the official patch from OpenHarmony when released.
• Upgrade to a patched version of OpenHarmony (v5.0.4 or later).
• Conduct a security audit of the kernel and privileged services for similar race conditions.

Workarounds (if patching is not possible):

• Use mandatory access control (MAC) systems like SELinux to confine low-privileged processes.
• Disable unnecessary services that may expose race condition vectors.

Valters IT
DevSecOps & Cyber Threat Intelligence