CVE-2025-27562

Executive Summary

CVE-2025-27562 is a Denial of Service (DoS) vulnerability affecting OpenHarmony versions 5.0.3 and prior. The flaw resides in improper memory release mechanisms, allowing a local attacker with low privileges to exhaust system memory resources, leading to a system crash or hang. The vulnerability is classified as CWE-401 (Missing Release of Memory after Effective Lifetime). With a CVSS score of 3.3 (Low), the impact is limited to availability, requiring local access and low privileges. No public exploit code or proof-of-concept is currently available, and the patch status remains unknown.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
• Base Score: 3.3 (Low)
• Attack Vector: Local (AV:L) – The attacker must have local access to the system.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: Low (PR:L) – The attacker needs basic user privileges.
• User Interaction: None (UI:N) – No user action is needed.
• Scope: Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality Impact: None (C:N) – No data exposure.
• Integrity Impact: None (I:N) – No data modification.
• Availability Impact: Low (A:L) – System performance degradation or temporary denial of service.

Threat Level: Low. The requirement for local access and low privileges reduces the attack surface. However, in multi-tenant or shared environments, this could be leveraged to disrupt services.

Deep Dive & Mechanics

The vulnerability is rooted in improper memory management within OpenHarmony’s kernel or system services. When a local attacker triggers a specific sequence of system calls or operations, the kernel fails to release allocated memory blocks after they are no longer needed. Over time, this memory leak accumulates, exhausting available memory and causing the system to become unresponsive or crash.

Root Cause Analysis:

• CWE-401: Missing Release of Memory after Effective Lifetime.
• Affected Component: Likely a system service or kernel module responsible for handling user requests or inter-process communication (IPC).
• Trigger Mechanism: A local attacker repeatedly invokes a specific API or system call that allocates memory but does not free it upon completion. The exact trigger is not publicly documented.

Attack Flow:

1. Attacker gains local access to an OpenHarmony device (e.g., via a compromised app or shell).
2. Attacker executes a script or binary that repeatedly calls the vulnerable function.
3. Each call allocates a small amount of memory that is never freed.
4. Over time, memory consumption grows, eventually exhausting system resources.
5. The system becomes unresponsive, crashes, or triggers an Out-Of-Memory (OOM) killer, leading to denial of service.

Vulnerable vs. Patched Code

Since no patch is available, a generic comparison is provided based on the vulnerability type.

Vulnerable Code (Conceptual):

void vulnerable_function() {
    void *buffer = malloc(1024);
    // Process data but forget to free buffer
    // Missing: free(buffer);
}

Patched Code (Expected):

void patched_function() {
    void *buffer = malloc(1024);
    // Process data
    free(buffer); // Properly release memory
}

Key Difference: The patched version ensures that every allocated memory block is freed after use, preventing memory leaks.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Local access to an OpenHarmony device (version ≤ 5.0.3).
• Low-privilege user account or ability to execute arbitrary code.

Exploitation Steps:

1. Identify Vulnerable Endpoint: Use system call tracing (e.g., strace) to identify functions that allocate memory without freeing.
2. Craft Exploit Script: Write a script that repeatedly calls the vulnerable function.

   #!/bin/bash
   while true; do
       # Replace with actual vulnerable command
       vulnerable_command
   done
   

3. Execute Exploit: Run the script in the background.

   ./exploit.sh &
   

4. Monitor Impact: Use free -m or top to observe memory exhaustion. The system will eventually become unresponsive.

Expected Outcome: System crash or hang, requiring a hard reset.

Blue Team (Defense & Detection)

Detection:

• Monitor memory usage trends for abnormal growth.
• Alert on repeated calls to suspicious system calls or APIs.

Mitigation:

• Restrict local user privileges.
• Implement resource limits (e.g., ulimit).
• Apply memory quotas per process.

Hunting Queries:

• Sysmon: Event ID 10 (ProcessAccess) for unusual memory allocation patterns.
• Auditd: Monitor for malloc/free imbalance using custom audit rules.

Indicators of Compromise (IOCs)

• Memory Usage: Sustained high memory consumption (>90%) without corresponding process activity.
• System Logs: Repeated OOM killer messages in dmesg.
• Process Behavior: A process repeatedly invoking system calls without termination.
• File Hashes: (None available, but any script or binary that triggers the vulnerability should be flagged.)

Detection Engineering

YARA Rule

rule CVE_2025_27562_Memory_Leak {
    meta:
        description = "Detects potential exploitation of CVE-2025-27562 via memory leak patterns"
        author = "Valters IT"
        date = "2025-03-20"
        reference = "CVE-2025-27562"
    strings:
        $s1 = "malloc" nocase
        $s2 = "free" nocase
        $s3 = "while" nocase
        $s4 = "true" nocase
    condition:
        all of ($s1,$s2,$s3,$s4) and #s1 > 100
}

Sigma Rule

title: CVE-2025-27562 Memory Exhaustion Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects repeated memory allocation without deallocation indicative of CVE-2025-27562 exploitation
author: Valters IT
date: 2025-03-20
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/bash'
        CommandLine|contains: 'while true'
    condition: selection
falsepositives:
    - Legitimate scripts with infinite loops
level: medium

Suricata Rule

alert ip any any -> any any (msg:"CVE-2025-27562 Potential Memory Leak Exploit"; content:"|77 68 69 6c 65 20 74 72 75 65|"; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict Local Access: Limit user accounts and enforce least privilege.
2. Monitor Memory: Set up alerts for abnormal memory consumption.
3. Apply Resource Limits: Use ulimit -v to cap virtual memory per process.

Long-Term Fix:

• Await an official patch from OpenHarmony. Once released, apply immediately.
• If possible, disable or restrict access to the vulnerable component.

Workaround:

• Implement a watchdog script that kills processes consuming excessive memory.
• Reboot the system periodically to clear memory leaks.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.