CVE-2025-25217

Executive Summary

CVE-2025-25217 is a denial-of-service (DoS) vulnerability in OpenHarmony versions up to and including v5.0.3. The flaw is triggered by a NULL pointer dereference, allowing a local attacker to crash the system. 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 patch details are available at this time.

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)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: None (C:N)
• Integrity Impact: None (I:N)
• Availability Impact: Low (A:L)

The threat level is low due to the requirement for local access and low privileges, and the impact being limited to availability.

Deep Dive & Mechanics

The vulnerability resides in OpenHarmony’s kernel or system service layer, where a NULL pointer dereference occurs when a local attacker sends a crafted request or triggers a specific system call. This leads to a kernel panic or service crash, causing a denial of service. The exact component is not disclosed, but the issue is reproducible on all versions up to v5.0.3.

Vulnerable vs. Patched Code

No patch is currently available. The vulnerable code path involves a pointer that is not properly validated before dereference. A hypothetical fix would add a NULL check before using the pointer.

Vulnerable Code (pseudo):

void process_request(struct request *req) {
    struct data *d = req->data;
    // No NULL check
    d->value = 10; // NULL pointer dereference if d is NULL
}

Patched Code (pseudo):

void process_request(struct request *req) {
    struct data *d = req->data;
    if (d == NULL) {
        return -EINVAL;
    }
    d->value = 10;
}

Exploitation & Lab Setup

Red Team

No public exploit code exists. An attacker with local access and low privileges could craft a malicious input to trigger the NULL pointer dereference. Example proof-of-concept (conceptual):

// Trigger NULL pointer dereference
int fd = open("/dev/vulnerable_device", O_RDWR);
struct malicious_input input;
input.data = NULL; // Force NULL pointer
ioctl(fd, IOCTL_CMD, &input);

Blue Team

To detect exploitation attempts, monitor for kernel panics or service crashes in logs. Use the following detection rules.

Indicators of Compromise (IOCs)

• Log Entries: Kernel NULL pointer dereference errors in dmesg or system logs.
• Crash Dumps: Core dumps or crash reports from the affected service.
• System Behavior: Unexpected reboots or service restarts.

Detection Engineering

YARA Rule

rule CVE_2025_25217_NULL_PTR {
    meta:
        description = "Detects NULL pointer dereference patterns in OpenHarmony"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $null_check = "if (ptr == NULL)" nocase
        $deref = "ptr->" nocase
    condition:
        $null_check and #deref > 5
}

Sigma Rule

title: OpenHarmony NULL Pointer Dereference
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects kernel NULL pointer dereference events
logsource:
    product: linux
    service: kernel
detection:
    selection:
        EventID: 1
        Message|contains: "NULL pointer dereference"
    condition: selection
falsepositives:
    - Rare kernel bugs
level: medium

Suricata Rule

alert ip any any -> any any (msg:"CVE-2025-25217 NULL Pointer Dereference Attempt"; content:"|00 00 00 00|"; depth:4; sid:1000001; rev:1;)

Remediation & Mitigation

• Patch: No official patch available. Monitor OpenHarmony security advisories for updates.
• Mitigation: Restrict local access to trusted users only. Disable vulnerable services if possible.
• Workaround: Apply kernel hardening (e.g., KASLR, SMAP/SMEP) to reduce impact.

Valters IT
DevSecOps & Cyber Threat Intelligence