Vulnerabilities > CVE-2022-31207 - Improper Verification of Cryptographic Signature vulnerability in Omron products
Summary
The Omron SYSMAC Cx product family PLCs (CS series, CJ series, and CP series) through 2022-05-18 lack cryptographic authentication. They utilize the Omron FINS (9600/TCP) protocol for engineering purposes, including downloading projects and control logic to the PLC. This protocol has authentication flaws as reported in FSCT-2022-0057. Control logic is downloaded to PLC volatile memory using the FINS Program Area Read and Program Area Write commands or to non-volatile memory using other commands from where it can be loaded into volatile memory for execution. The logic that is loaded into and executed from the user program area exists in compiled object code form. Upon execution, these object codes are first passed to a dedicated ASIC that determines whether the object code is to be executed by the ASIC or the microprocessor. In the former case, the object code is interpreted by the ASIC whereas in the latter case the object code is passed to the microprocessor for object code interpretation by a ROM interpreter. In the abnormal case where the object code cannot be handled by either, an abnormal condition is triggered and the PLC is halted. The logic that is downloaded to the PLC does not seem to be cryptographically authenticated, thus allowing an attacker to manipulate transmitted object code to the PLC and either execute arbitrary object code commands on the ASIC or on the microprocessor interpreter.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| OS | 7 | |
| Hardware | 7 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Padding Oracle Crypto Attack An attacker is able to efficiently decrypt data without knowing the decryption key if a target system leaks data on whether or not a padding error happened while decrypting the ciphertext. A target system that leaks this type of information becomes the padding oracle and an attacker is able to make use of that oracle to efficiently decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block). In addition to performing decryption, an attacker is also able to produce valid ciphertexts (i.e., perform encryption) by using the padding oracle, all without knowing the encryption key. Any cryptosystem can be vulnerable to padding oracle attacks if the encrypted messages are not authenticated to ensure their validity prior to decryption, and then the information about padding error is leaked to the attacker. This attack technique may be used, for instance, to break CAPTCHA systems or decrypt/modify state information stored in client side objects (e.g., hidden fields or cookies). This attack technique is a side-channel attack on the cryptosystem that uses a data leak from an improperly implemented decryption routine to completely subvert the cryptosystem. The one bit of information that tells the attacker whether a padding error during decryption has occurred, in whatever form it comes, is sufficient for the attacker to break the cryptosystem. That bit of information can come in a form of an explicit error message about a padding error, a returned blank page, or even the server taking longer to respond (a timing attack). This attack can be launched cross domain where an attacker is able to use cross-domain information leaks to get the bits of information from the padding oracle from a target system / service with which the victim is communicating. To do so an attacker sends a request containing ciphertext to the target system. Due to the browser's same origin policy, the attacker is not able to see the response directly, but can use cross-domain information leak techniques to still get the information needed (i.e., information on whether or not a padding error has occurred). For instance, this can be done using "img" tag plus the onerror()/onload() events. The attacker's JavaScript can make web browsers to load an image on the target site, and know if the image is loaded or not. This is 1-bit information needed for the padding oracle attack to work: if the image is loaded, then it is valid padding, otherwise it is not.