Zyxel security advisory for FragAttacks against WiFi products
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. There are twelve CVEs reported by Wi-Fi Alliance®, namely:
- CVE-2020-26139: Forwarding EAPOL frames even though the sender is not yet authenticated (should only affect APs).
- CVE-2020-26140: Accepting plaintext data frames in a protected network.
- CVE-2020-26141: Not verifying the TKIP MIC of fragmented frames.
- CVE-2020-26142: Processing fragmented frames as full frames.
- CVE-2020-26143: Accepting fragmented plaintext data frames in a protected network.
- CVE-2020-26144: Accepting plaintext A-MSDU frames that start with an RFC1042 header with EtherType EAPOL (in an encrypted network).
- CVE-2020-26145: Accepting plaintext broadcast fragments as full frames (in an encrypted network).
- CVE-2020-26146: Reassembling encrypted fragments with non-consecutive packet numbers.
- CVE-2020-26147: Reassembling mixed encrypted/plaintext fragments.
- 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.
It is important to note that exploiting these weaknesses is not a trivial task. Specifically, an attacker has to be physically within the wireless range of the vulnerable device, obtain a man-in-the-middle position, and entice user interaction to get the user to click or visit a compromised website. According to Wi-Fi Alliance®, there is currently no evidence of the vulnerabilities being used maliciously against WiFi users.
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 affected model list. 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.
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.
1. Enable WPA2/WPA3 for wireless connections.
2. Use strong, unique connection passwords for every service set identifier (SSID) and change them regularly.
3. Enable firewall rules on the affected device or its connected gateway/firewall, if any.
Got a question?
Please contact your local service rep or comment as below.
2021-5-12: Initial release
2021-05-17: Updated the vulnerability description, general security practices, and the patch plan of CPE
2021-06-11: Updated the vulnerability description and the affected model list and patch plan of CPE, WiFi system and firewalls.