Zyxel security advisory for FragAttacks against WiFi products

CVE: CVE-2020-24586, CVE-2020-24587, CVE-2020-24588

Summary

Zyxel is aware of the FRagmentation and AGgregation Attacks against WiFi vulnerability (dubbed “FragAttacks”) and is releasing patches for some vulnerable WiFi products. Users are advised to adopt the applicable firmware updates or follow the advice below for optimal protection.

What is the vulnerability?

The FragAttacks vulnerability was identified in the IEEE 802.11 implementation of de-aggregation and de-fragmentation of frames at the receiver in some WiFi devices. Of the twelve CVEs reported by Wi-Fi Alliance®, three affect Zyxel products, namely:

• CVE-2020-24586: Not clearing fragments from memory when (re)connecting to a network
• CVE-2020-24587: Reassembling fragments encrypted under different keys
• CVE-2020-24588: Accepting non-SPP A-MSDU frames

Please refer to the official CVEs for the technical details and severity. Zyxel products are NOT affected by the nine other CVEs (CVE-2020-26139 - CVE-2020-26147) either because they do not use the vulnerable packages or their vulnerable versions.

It is important to note that an attacker has to be physically within the wireless range of the vulnerable device to exploit these weaknesses, thus the impact is relatively limited. According to Wi-Fi Alliance®, there is currently no evidence of the vulnerabilities being used against WiFi users maliciously.

What versions are vulnerable—and what should you do?

After a thorough investigation, we’ve identified the affected products that are within their warranty and support period, as shown in the link here. We are already working with WiFi chip vendors to prepare the patches and will continue to update the advisory as additional information becomes available. We urge users to install the applicable updates when available for optimal protection.

Please note that the table in the link provided does NOT include customized models for internet service providers (ISPs).

If you are an ISP, please contact your Zyxel sales or service representative for further details.

If you are an end-user who received your Zyxel device from an ISP, please reach out to the ISP’s support team directly, as the device may have custom-built settings.

If you are an end-user who purchased your Zyxel device yourself, please contact your local Zyxel support team or visit our forum for further assistance.

For those vulnerable products with chips and drivers no longer supported by WiFi chip vendors, we recommend that users follow the general security practices below or upgrade their models.