Abode Systems, Inc. iota All-In-One Security Kit is a popular smart home security hub, well-known for its robust features and wireless setup. However, versions 6.9Z and 6.9X are affected by a critical set of vulnerabilities cataloged as CVE-2022-35887, relating to format string injections in the wireless connection setup process. This vulnerability can expose users to memory corruption, information leakage, or even a full Denial of Service (DoS) with a single HTTP request. This long-read walks you through the technical side of the bug, details how it can be exploited, and links you to must-read references.

Background

Format string vulnerabilities occur when user-controlled input is unsafely formatted into strings used in C-like languages. Abode’s iota security platform uses a web interface for configuring wireless settings, which receives HTTP requests at the /action/wirelessConnect endpoint. Here, a vulnerable parameter called default_key_id gets unsafely used.

Type: Format String Injection

- Affected Component: Web UI /action/wirelessConnect
- Product/Versions: Abode iota All-In-One Security Kit firmware 6.9Z, 6.9X

Input Vector: Authenticated HTTP POST request, via default_key_id parameter

- CVSS: High (See NVD Entry)

Technical Details

Inside the handler function for /action/wirelessConnect, the firmware retrieves the user’s submitted default_key_id and directly incorporates it in a string formatting operation—without sanitization or input-validation.

Example: Vulnerable C Code Snippet

// Pseudo-code of vulnerable handler
void handle_wireless_connect(HttpRequest *req) {
    char buffer[256];
    const char *user_key_id = req->get_param("default_key_id");

    // Vulnerable: user input used as format string!
    sprintf(buffer, user_key_id);

    // further logic...
}


If an attacker provides a malicious format string as default_key_id (like %x %x %x %x), the function will process it, leaking stack memory, or worse, manipulating memory.

1. Sending a Malicious POST Request

POST /action/wirelessConnect HTTP/1.1
Host: <target>
Content-Type: application/x-www-form-urlencoded
Cookie: session=<auth session>

default_key_id=%x-%x-%x-%x

Memory Disclosure: Heap or stack content will be exposed in the web interface response or logs.

- Crash/DoS: Special format strings like %n can write to arbitrary memory, possibly crashing the process.

3. Real-World Impact

An attacker who has gained authentication (which may be less of a barrier in some IoT scenarios) can cause the device to:

Authenticated session (login credentials)

Craft a POST request as shown above with a specially-crafted default_key_id. Monitor the device for abnormal behavior, crashes, or suspicious output in responses.

Mitigation

Abode has released firmware updates resolving this vulnerability. Always ensure your IoT devices run the latest available firmware.

Validate all user input before using it in format strings.

- Prefer safer functions like snprintf with format strings controlled by the developer, not the user.

References

- National Vulnerability Database: CVE-2022-35887
- Original ZDI Advisory
- Abode Website

Conclusion

CVE-2022-35887 is a classic, but dangerous, format string bug in a modern smart home security hub. It’s a lesson that even familiar, well-used IoT products can have old-school C software failures lurking inside. Always update your devices and be wary of unusual interface behaviors.

Timeline

Published on: 10/25/2022 17:15:00 UTC
Last modified on: 10/27/2022 15:16:00 UTC