Hitachi Energy PCU400
1. EXECUTIVE SUMMARY
- CVSS v3 7.5
- ATTENTION: Exploitable remotely/low attack complexity
- Vendor: Hitachi Energy
- Equipment: PCU400, PCULogger
- Vulnerabilities: Access of Resource Using Incompatible Type (‘Type Confusion’), NULL Pointer Dereference, Use After Free, Double Free, Observable Discrepancy, Out-of-bounds Read
2. RISK EVALUATION
Exploitation of these vulnerabilities could allow an attacker to access or decrypt sensitive data, crash the device application, or cause a denial-of-service condition.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Hitachi Energy reports that the following products are affected:
- PCU400: Version 6.5 K and prior
- PCU400: Version 9.4.1 and prior
- PCULogger: Version 1.1.0 and prior
3.2 VULNERABILITY OVERVIEW
3.2.1 ACCESS OF RESOURCE USING INCOMPATIBLE TYPE (‘TYPE CONFUSION’) CWE-843
There is a type confusion vulnerability relating to X.400 address processing inside an X.509 GeneralName. X.400 addresses were parsed as an ASN1_STRING but the public structure definition for GENERAL_NAME incorrectly specified the type of the x400Address field as ASN1_TYPE. This field is subsequently interpreted by the OpenSSL function GENERAL_NAME_cmp as an ASN1_TYPE rather than an ASN1_STRING. When CRL checking is enabled (i.e. the application sets the X509_V_FLAG_CRL_CHECK flag), this vulnerability may allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or enact a denial-of-service. In most cases, the attack requires the attacker to provide both the certificate chain and CRL, neither of which need to have a valid signature. If the attacker only controls one of these inputs, the other input must already contain an X.400 address as a CRL distribution point, which is uncommon. As such, this vulnerability is most likely to only affect applications which have implemented their own functionality for retrieving CRLs over a network.
CVE-2023-0286 has been assigned to this vulnerability. A CVSS v3 base score of 7.4 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H).
3.2.2 NULL POINTER DEREFERENCE CWE-476
An invalid pointer dereference on read can be triggered when an application tries to check a malformed DSA public key by the EVP_PKEY_public_check() function. This will most likely lead to an application crash. This function can be called on public keys supplied from untrusted sources which could allow an attacker to cause a denial-of-service attack. The TLS implementation in OpenSSL does not call this function but applications might call the function if there are additional security requirements imposed by standards such as FIPS 140-3.
CVE-2023-0217 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
3.2.3 NULL POINTER DEREFERENCE CWE-476
An invalid pointer dereference on read can be triggered when an application tries to load malformed PKCS7 data with the d2i_PKCS7(), d2i_PKCS7_bio() or d2i_PKCS7_fp() functions. The result of the dereference is an application crash which could lead to a denial-of-service attack. The TLS implementation in OpenSSL does not call this function however third party applications might call these functions on untrusted data.
CVE-2023-0216 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
3.2.4 NULL POINTER DEREFERENCE CWE-476
A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. In case the hash algorithm used for the signature is known to the OpenSSL library but the implementation of the hash algorithm is not available, the digest initialization will fail. There is a missing check for the return value from the initialization function which later leads to invalid usage of the digest API most likely leading to a crash. The unavailability of an algorithm can be caused by using FIPS enabled configuration of providers or more commonly by not loading the legacy provider. PKCS7 data is processed by the SMIME library calls and also by the time stamp (TS) library calls. The TLS implementation in OpenSSL does not call these functions, however third party applications would be affected if they call these functions to verify signatures on untrusted data.
CVE-2023-0401 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
3.2.5 USE AFTER FREE CWE-416
The public API function BIO_new_NDEF is a helper function used for streaming ASN.1 data via a BIO. It is primarily used internally to OpenSSL to support the SMIME, CMS and PKCS7 streaming capabilities, but may also be called directly by end user applications. The function receives a BIO from the caller, prepends a new BIO_f_asn1 filter BIO onto the front of it to form a BIO chain, and then returns the new head of the BIO chain to the caller. Under certain conditions, for example if a CMS recipient public key is invalid, the new filter BIO is freed and the function returns a NULL result indicating a failure. However, in this case, the BIO chain is not properly cleaned up and the BIO passed by the caller still retains internal pointers to the previously freed filter BIO. If the caller then goes on to call BIO_pop() on the BIO then a use-after-free will occur. This will most likely result in a crash. This scenario occurs directly in the internal function B64_write_ASN1() which may cause BIO_new_NDEF() to be called and will subsequently call BIO_pop() on the BIO. This internal function is in turn called by the public API functions PEM_write_bio_ASN1_stream, PEM_write_bio_CMS_stream, PEM_write_bio_PKCS7_stream, SMIME_write_ASN1, SMIME_write_CMS and SMIME_write_PKCS7. Other public API functions that may be impacted by this include i2d_ASN1_bio_stream, BIO_new_CMS, BIO_new_PKCS7, i2d_CMS_bio_stream and i2d_PKCS7_bio_stream. The OpenSSL cms and smime command line applications are similarly affected.
CVE-2023-0215 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
3.2.6 DOUBLE FREE CWE-415
The function PEM_read_bio_ex() reads a PEM file from a BIO and parses and decodes the “name” (e.g. CERTIFICATE”), any header data and the payload data. If the function succeeds then the “name_out”, “header” and “data” arguments are populated with pointers to buffers containing the relevant decoded data. The caller is responsible for freeing those buffers. It is possible to construct a PEM file that results in 0 bytes of payload data. In this case PEM_read_bio_ex() will return a failure code but will populate the header argument with a pointer to a buffer that has already been freed. If the caller also frees this buffer then a double free will occur. This will most likely lead to a crash. This could be exploited by an attacker who has the ability to supply malicious PEM files for parsing to achieve a denial-of-service attack. The functions PEM_read_bio() and PEM_read() are simple wrappers around PEM_read_bio_ex() and therefore these functions are also directly affected. These functions are also called indirectly by a number of other OpenSSL functions including PEM_X509_INFO_read_bio_ex() and SSL_CTX_use_serverinfo_file() which are also vulnerable. Some OpenSSL internal uses of these functions are not vulnerable because the caller does not free the header argument if PEM_read_bio_ex() returns a failure code. These locations include the PEM_read_bio_TYPE() functions as well as the decoders introduced in OpenSSL 3.0. The OpenSSL asn1parse command line application is also impacted by this issue.
CVE-2022-4450 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
3.2.7 OBSERVABLE DISCREPANCY CWE-203
A timing-based side channel exists in the OpenSSL RSA decryption implementation which could be sufficient to recover plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption, an attacker would have to be able to send a very large number of trial messages for decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An attacker that had observed a genuine connection between a client and a server could use this flaw to send trial messages to the server and record the time taken to process them. After a sufficiently large number of messages the attacker could recover the pre-master secret used for the original connection and thus be able to decrypt the application data sent over that connection.
CVE-2022-4304 has been assigned to this vulnerability. A CVSS v3 base score of 5.9 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N).
3.2.8 OUT-OF-BOUNDS READ CWE-125
A read buffer overrun can be triggered in X.509 certificate verification, specifically in name constraint checking. Note that this occurs after certificate chain signature verification and requires either a CA to have signed the malicious certificate or for the application to continue certificate verification despite failure to construct a path to a trusted issuer. The read buffer overrun might result in a crash which could lead to a denial-of-service attack. In theory it could also result in the disclosure of private memory contents (such as private keys, or sensitive plaintext) although we are not aware of any working exploit leading to memory contents disclosure as of the time of release of this advisory. In a TLS client, this can be triggered by connecting to a malicious server. In a TLS server, this can be triggered if the server requests client authentication and a malicious client connects.
CVE-2022-4203 has been assigned to this vulnerability. A CVSS v3 base score of 4.9 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).
3.3 BACKGROUND
- CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Switzerland
3.4 RESEARCHER
A researcher from Dragos reported these vulnerabilities to Hitachi Energy.
4. MITIGATIONS
Hitachi Energy has identified the following specific workarounds and mitigations users can apply to reduce risk:
- PCU400 versions 6.5 K and below: If IEC62351-3 secure for IEC104/DNP3 is used, then update to version 6.6.0 or later.
- PCU400 versions 9.4.1 and below: If IEC62351-3 secure for IEC104/DNP3 is used, then update to version 9.4.2 or later.
- PCULogger versions 1.1.0 and below: If the PCULogger program is used, then update to version 1.2.0* when available. This version is compatible with PCU400 9.4.2 and later.
For more information see the associated Hitachi Energy PSIRT security advisory 8dbd000213 CYBERSECURITY ADVISORY – OpenSSL Vulnerabilities in Hitachi Energy PCU400 Product.
Hitachi Energy recommends users implement recommended security practices and firewall configurations to help protect the process control network from attacks originating from outside the network. Process control systems should be physically protected from direct access by unauthorized personnel, have no direct connections to the Internet, and be separated from other networks by means of a firewall system with a minimal number of ports exposed. Process control systems should not be used for Internet surfing, instant messaging, or receiving e-mails. Portable computers and removable storage media should be carefully scanned for viruses before they are connected to a control system.
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities. CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.
No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.
5. UPDATE HISTORY
- March 6, 2025: Initial Publication