​Siemens SIMATIC MV500 Devices

1. EXECUTIVE SUMMARY

• ​CVSS v3 8.2
• ​ATTENTION: Exploitable remotely/low attack complexity
• ​Vendor: Siemens
• ​Equipment: SIMATIC MV500 series devices
• ​Vulnerabilities: Exposure of Sensitive Information to an Unauthorized Actor, Missing Release of Memory after Effective Lifetime, Injection, Inadequate Encryption Strength, Double Free, Incomplete Cleanup, Observable Discrepancy, Improper Locking, Use After Free, Improper Input Validation

2. RISK EVALUATION

​Successful exploitation of these vulnerabilities could allow an attacker to read memory contents, disclose information, or cause a denial-of-service condition.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

​The following products from Siemens are affected:

• ​SIMATIC MV540 H (6GF3540-0GE10): All versions prior to v3.3.4
• ​SIMATIC MV540 S (6GF3540-0CD10): All versions prior to v 3.3.4
• ​SIMATIC MV550 H (6GF3550-0GE10): All versions prior to v 3.3.4
• ​SIMATIC MV550 S (6GF3550-0CD10): All versions prior to v 3.3.4
• ​SIMATIC MV560 U (6GF3560-0LE10): All versions prior to v 3.3.4
• ​SIMATIC MV560 X (6GF3560-0HE10): All versions prior to v 3.3.4

3.2 VULNERABILITY OVERVIEW

3.2.1 ​EXPOSURE OF SENSITIVE INFORMATION TO AN UNAUTHORIZED ACTOR CWE-200

​An information leak flaw was found in NFS over RDMA in the net/sunrpc/xprtrdma/rpc_rdma.c in the Linux kernel. This flaw allows an attacker with normal user privileges to leak kernel information.

​CVE-2022-0812 has been assigned to this vulnerability. A CVSS v3 base score of 4.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).

3.2.2 ​MISSING RELEASE OF MEMORY AFTER EFFECTIVE LIFETIME CWE-401

​A memory leak problem was found in the TCP source port generation algorithm in net/ipv4/tcp.c due to the small table perturb size. This flaw may allow an attacker to information leak and may cause a denial-of-service problem.

​CVE-2022-1012 has been assigned to this vulnerability. A CVSS v3 base score of 8.2 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H).

3.2.3 ​IMPROPER NEUTRALIZATION OF SPECIAL ELEMENTS IN OUTPUT USED BY A DOWNSTREAM COMPONENT ('INJECTION') CWE-74

​Guests can trigger NIC interface reset/abort/crash via netback It is possible for a guest to trigger a NIC interface reset/abort/crash in a Linux based network backend by sending certain kinds of packets. It appears to be an (unwritten?) assumption in the rest of the Linux network stack that packet protocol headers are all contained within the linear section of the SKB and some NICs behave badly if this is not the case. This has been reported to occur with Cisco (enic) and Broadcom NetXtrem II BCM5780 (bnx2x) though it may be an issue with other NICs/drivers as well. In case the frontend is sending requests with split headers, netback will forward those violating above mentioned assumption to the networking core, resulting in said misbehavior.

​CVE-2022-3643 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H).

3.2.4 ​INADEQUATE ENCRYPTION STRENGTH CWE-326

​A timing-based side channel exists in the OpenSSL RSA decryption implementation which could be sufficient to recover a 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 (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N).

3.2.5 ​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 5.9 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.6 ​INCOMPLETE CLEANUP CWE-459

​Incomplete cleanup of multi-core shared buffers for some Intel(R) processors may allow an authenticated user to potentially enable information disclosure via local access.

​CVE-2022-21123 has been assigned to this vulnerability. A CVSS v3 base score of 5.5 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N).

3.2.7 ​INCOMPLETE CLEANUP CWE-459

​Incomplete cleanup of microarchitectural fill buffers on some Intel(R) processors may allow an authenticated user to potentially enable information disclosure via local access.

​CVE-2022-21125 has been assigned to this vulnerability. A CVSS v3 base score of 5.5 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N).

3.2.8 ​INCOMPLETE CLEANUP CWE-459

​Incomplete cleanup in specific special register write operations for some Intel(R) processors may allow an authenticated user to potentially enable information disclosure via local access.

​CVE-2022-21166 has been assigned to this vulnerability. A CVSS v3 base score of 5.5 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N).

3.2.9 ​OBSERVABLE DISCREPANCY CWE-203

​The Linux kernel before 5.17.9 allows TCP servers to identify clients by observing what source ports are used. This occurs because of the use of Algorithm 4 ("double-hash port selection algorithm") of RFC 6056.

​CVE-2022-32296 has been assigned to this vulnerability. A CVSS v3 base score of 3.3 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).

3.2.10 ​IMPROPER LOCKING CWE-667

​Guests can trigger deadlock in Linux netback driver. The patch for XSA-392 introduced another issue which might result in a deadlock when trying to free the SKB of a packet dropped due to the XSA-392 handling (CVE-2022-42328). Additionally, when dropping packages for other reasons the same deadlock could occur in case of netpoll being active for the interface the xen-netback driver is connected to (CVE-2022-42329).

​CVE-2022-42328 has been assigned to this vulnerability. A CVSS v3 base score of 5.5 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

3.2.11 ​IMPROPER LOCKING CWE-667

​Guests can trigger deadlock in Linux netback drive. The patch for XSA-392 introduced another issue which might result in a deadlock when trying to free the SKB of a packet dropped due to the XSA-392 handling (CVE-2022-42328). Additionally, when dropping packages for other reasons the same deadlock could occur in case of netpoll being active for the interface the xen-netback driver is connected to (CVE-2022-42329).

​CVE-2022-42329 has been assigned to this vulnerability. A CVSS v3 base score of 5.5 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

3.2.12 ​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 5.9 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.13 ​IMPROPER INPUT VALIDATION CWE-20

​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 needs 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 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H).

3.3 BACKGROUND

• ​CRITICAL INFRASTRUCTURE SECTORS: Multiple Sectors
• ​COUNTRIES/AREAS DEPLOYED: Worldwide
• ​COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

​Siemens reported these vulnerabilities to CISA.

4. MITIGATIONS

​Siemens recommends users update their SIMATIC MV500 series devices to the following version or latest version of their software:

• ​Update to V3.3.4 or later version

​As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. To operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens' operational guidelines for industrial security and following recommendations in the product manuals.

​Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage.

​For further inquiries on security vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT.

​For more information see the associated Siemens security advisory SSA-561322 in HTML and CSAF.

​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 at cisa.gov/ics. 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.

​Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics 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 exploits specifically target these vulnerabilities.