CVE-2023-51839

Vulnerability

Description

DeviceFarmer STF (Smartphone Test Farm) version 3.6.6 employs the Data Encryption Standard in Electronic Codebook mode (DES-ECB) for VNC authentication, as identified in the file lib/util/vncauth.js [3]. DES-ECB is a broken and risky cryptographic algorithm that uses a fixed 56-bit key without an initialization vector, making it susceptible to pattern recognition and brute-force attacks [4]. This weakness is classified as CWE-327: Use of a Broken or Risky Cryptographic Algorithm [2].

Exploitation

An attacker with network access to the STF service can exploit this vulnerability remotely without authentication [4]. Because DES-ECB encrypts identical plaintext blocks into identical ciphertext blocks, an observer can infer patterns in the encrypted data, potentially revealing authentication credentials or other sensitive information. The vulnerability is present in the VNC authentication mechanism, which is used to secure remote device control sessions [1].

Impact

Successful exploitation leads to information disclosure and escalation of privileges [4]. An attacker could decrypt intercepted VNC traffic to obtain session keys or passwords, then impersonate legitimate users or gain unauthorized access to connected Android devices. This compromises the confidentiality and integrity of data transmitted between the browser and the managed devices.

Mitigation

As of the publication date, the vendor has not released an official patch for CVE-2023-51839 [2]. Users are advised to disable the VNC feature if not required, or to implement additional network-layer protections such as VPN or TLS to encrypt traffic. Upgrading to a version that replaces DES-ECB with a modern algorithm (e.g., AES-GCM) is recommended once available.