In-Depth Analysis of Attacks on Vulnerability CVE-2023-33538 in Wi-Fi Routers

Summary: Automated scans and active probes targeting CVE-2023-33538 were detected, an exploit targeting end-of-life TP-Link Wi-Fi router models, using Mirai-type malicious payloads.

This investigation demonstrates that while active botnet attacks use flawed exploit code, the vulnerability remains a practical infection vector due to the widespread use of IoT default credentials.

The analysis revealed two key facts: although the observed attacks in the wild were flawed and would have failed, the underlying vulnerability is real. Furthermore, successful exploitation requires authentication on the router's web interface.

To determine the impact of these attacks, an exhaustive investigation was conducted by emulating the TP-Link TL-WR940N router. Through firmware emulation and reverse engineering, the exploits were analyzed to see if the payload could successfully execute on that device model.

The observed payloads are malicious binaries characteristic of Mirai-type botnets, designed to be downloaded and executed on vulnerable devices. This activity was observed after this CVE was included in CISA's Known Exploited Vulnerability (KEV) Catalog in June 2025.

Active scans and probes targeting vulnerability CVE-2023-33538 were identified, which affects several end-of-life TP-Link Wi-Fi router models, including the TL-WR940N v2 and v4.

Key facts

  • Automated scans were observed attempting to exploit CVE-2023-33538.
  • The vulnerability affects TP-Link Wi-Fi router models (e.g., TL-WR940N v2 and v4).
  • Exploitation requires authentication on the router's web interface.
  • Malicious payloads are Mirai-type binaries, associated with botnets.

Why it matters

Even if active botnet attacks fail, the fact that the underlying vulnerability is real and that IoT devices still use default credentials represents a significant risk. Attackers can leverage this security gap to initiate infection campaigns.