A recent vulnerability was discovered in OpenHarmony-v3.1.2 and prior versions that may lead to a Denial of Service (DoS) attack when a device attempts to join a network. Network attackers could exploit this vulnerability by sending an abnormal packet during the network joining process, causing a nullptr dereference and forcing the targeted device to reboot. This post will cover details of the vulnerability (CVE-2022-43495), provide code snippets to demonstrate the issue, and outline steps on how to mitigate and patch affected systems.

Vulnerability Details

The vulnerability exists in the distributedhardware_device_manager module of OpenHarmony-v3.1.2 and previous versions. When processing device join network requests, the system doesn’t properly validate the incoming packet, leading to a nullptr dereference, ultimately causing the targeted device to reboot. An attacker must be able to intercept and manipulate network traffic to exploit this vulnerability.

Here's a code snippet showcasing the vulnerable code

// distributedhardware_device_manager.c
// ...
void HandleJoinNetworkRequest(const Packet *packet) {
    JoinNetworkPayload payload;
    if (!ValidateJoinNetworkPacket(packet, &payload)) {
        // Handle invalid request
        return;
    }
    // ...
    HandleHardwareRequest(payload, nullptr); // here lies the nullptr dereference vulnerability
    // ...
}

This issue was assigned the identifier CVE-2022-43495.

Exploit

To exploit this vulnerability, a network attacker can craft a malicious packet with a specially designed payload that, when processed by the vulnerable distributedhardware_device_manager handling function, will trigger a nullptr reference leading to device reboot.

Here's a basic example of a crafted malicious packet that could potentially trigger the nullptr reference:

// attacker_code.c
#include "network_packet.h"

int main() {
    Packet maliciousPacket;
    // Craft malicious payload to trigger nullptr reference
    maliciousPacket.payload = "<malicious payload here>";
    
    // Send the malicious packet to the target device
    SendPacketToTargetDevice(maliciousPacket);
    return ;
}

Mitigation and Patch

To prevent this DoS vulnerability from being exploited, it's essential to apply the following patch to the OpenHarmony-v3.1.2 and prior versions' source code:

// distributedhardware_device_manager.c
// ...
void HandleJoinNetworkRequest(const Packet *packet) {
    JoinNetworkPayload payload;
    if (!ValidateJoinNetworkPacket(packet, &payload)) {
        // Handle invalid request
        return;
    }
    // ...
+   if (payload == nullptr) { // Patch - fix nullptr reference issue
+       // Handle invalid payload gracefully
+       return;
+   }
    HandleHardwareRequest(payload, nullptr);
    // ...
}

This patch adds a check for nullptr payloads ensuring that any malicious packets are discarded gracefully without causing the device to crash and reboot.

Conclusion

The DoS vulnerability in the distributedhardware_device_manager component of OpenHarmony-v3.1.2 and previous versions can result in device reboots when exploited by network attackers. Devices running the affected versions must apply the patch outlined in this post to mitigate the threat. For more information, please refer to the original references provided.

Timeline

Published on: 11/03/2022 20:15:00 UTC
Last modified on: 11/07/2022 02:12:00 UTC