ICSA-21-075-02: GE UR Family (Update A)
Prior to UR firmware Version 8.1x, UR supported various encryption and MAC algorithms for SSH communication, some of which are weak. The DES and Triple DES ciphers, as used in the TLS, SSH, and IPSec protocols and other protocols and products, have a birthday bound of approximately four billion blocks, which makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTPS session using Triple DES in CBC mode, aka a "Sweet32" attack. Prior to UR firmware Version 8.1x, UR supported various encryption and MAC algorithms for SSH communication, some of which are weak. The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for remote attackers to conduct plaintext-recovery attacks via statistical analysis of ciphertext in a large number of sessions that use the same plaintext. Prior to firmware Version 7.4x, UR supported only SSHv2. Starting from firmware Version 7.4x, UR added support to SSHv1. SSHv1 has known vulnerabilities (SSH protocol session key retrieval and insertion attack). SSH 1.2.25, 1.2.23, and other versions, when used in in CBC (Cipher Block Chaining) or CFB (Cipher Feedback 64 bits) modes, allows remote attackers to insert arbitrary data into an existing stream between an SSH client and server by using a known plaintext attack and computing a valid CRC-32 checksum for the packet, aka the "SSH insertion attack." GE UR firmware versions prior to version 8.1x web server interface is supported on UR over HTTP protocol. It allows sensitive information exposure without authentication. GE UR firmware versions prior to version 8.1x supports web interface with read-only access. The device fails to properly validate user input, making it possible to perform cross-site scripting attacks, which may be used to send a malicious script. Also, UR Firmware web server does not perform HTML encoding of user-supplied strings. GE UR firmware versions prior to version 8.1x web server task does not properly handle receipt of unsupported HTTP verbs, resulting in the web server becoming temporarily unresponsive after receiving a series of unsupported HTTP requests. When unresponsive, the web server is inaccessible. By itself, this is not particularly significant as the relay remains effective in all other functionality and communication channels. GE UR IED firmware versions prior to version 8.1x supports upgrading firmware using UR Setup configuration tool – Enervista UR Setup. This UR Setup tool validates the authenticity and integrity of firmware file before uploading the UR IED. An illegitimate user could upgrade firmware without appropriate privileges. The weakness is assessed, and mitigation is implemented in firmware Version 8.10. GE UR IED firmware versions prior to version 8.1x with "Basic" security variant does not allow the disabling of the "Factory Mode," which is used for servicing the IED by a "Factory" user. GE UR firmware versions prior to version 8.1x shares MODBUS memory map as part of the communications guide. GE was made aware a "Last-key pressed" MODBUS register can be used to gain unauthorized information. GE UR bootloader binary Version 7.00, 7.01 and 7.02 included unused hardcoded credentials. Additionally, a user with physical access to the UR IED can interrupt the boot sequence by rebooting the UR.
CVSS v3.1: 8.4