Bosch PSIRT

ctrlX Products affected by OpenSSL Vulnerability CVE-2020-1971

BOSCH-SA-274557

Advisory Information

  • Advisory ID: BOSCH-SA-274557
  • CVE Numbers and CVSS v3.1 Scores:
  • Published: 18 Dec 2020
  • Last Updated: 18 Dec 2020

Summary

The OpenSSL Software Foundation has published information [1] for OpenSSL versions prior to 1.1.1i (1.1.1 – 1.1.1h) and 1.0.2x (1.0.2 – 1.0.2w) regarding a weakness in the GENERAL_NAME_cmp function. The vulnerability could allow an attacker to provoke a null pointer dereference, potentially leading to a denial of service.

Multiple components of Bosch Rexroth are shipped with a vulnerable OpenSSL version.

The aforementioned function is not used directly by any Rexroth software component and therefore the risk of an attacker being able to exploit the vulnerability is considered as low. Nevertheless, it cannot be completely ruled out that the function might be called indirectly. It is therefore strongly advised to follow the suggested solution and mitigations.

Affected Products

  • ctrlX CORE Automation Core < 1.6.1
  • ctrlX CORE Runtime < XCR-V-0106.1
  • ctrlX WORKS < V0106.1

Solution and Mitigations

Software Update

For ctrlX CORE (+ the affected components) and ctrlX WORKS an updated release will be published in the near future and this Security Advisory will be updated as soon as the update becomes available. It is recommended that this update should be installed in a timely manner after the release, if possible.

Compensatory Measures

Compensatory measures are recommended which mitigate the risk are recommended until the update becomes available. Always define such compensatory measures individually, in the context of the operational environment. Some possible measures are described in the “Security Guideline Electric Drives and Controls”, for example the network segmentation (please see [2]). In general, it is highly recommended to implement the measures described in the “Security Guideline Electric Drives and Controls”.

Vulnerability Details

CVE-2020-1971

ctrlX products are shipped with OpenSSL versions vulnerable to CVE-2020-1971.

CVE description: The X.509 GeneralName type is a generic type for representing different types of names. One of those name types is known as EDIPartyName. OpenSSL provides a function GENERAL_NAME_cmp which compares different instances of a GENERAL_NAME to see if they are equal or not. This function behaves incorrectly when both GENERAL_NAMEs contain an EDIPARTYNAME. A NULL pointer dereference and a crash may occur leading to a possible denial of service attack. OpenSSL itself uses the GENERAL_NAME_cmp function for two purposes: 1) Comparing CRL distribution point names between an available CRL and a CRL distribution point embedded in an X509 certificate 2) When verifying that a timestamp response token signer matches the timestamp authority name (exposed via the API functions TS_RESP_verify_response and TS_RESP_verify_token) If an attacker can control both items being compared then that attacker could trigger a crash. For example if the attacker can trick a client or server into checking a malicious certificate against a malicious CRL then this may occur. Note that some applications automatically download CRLs based on a URL embedded in a certificate. This checking happens prior to the signatures on the certificate and CRL being verified. OpenSSL’s s_server, s_client and verify tools have support for the “-crl_download” option which implements automatic CRL downloading and this attack has been demonstrated to work against those tools. Note that an unrelated bug means that affected versions of OpenSSL cannot parse or construct correct encodings of EDIPARTYNAME. However it is possible to construct a malformed EDIPARTYNAME that OpenSSL’s parser will accept and hence trigger this attack. All OpenSSL 1.1.1 and 1.0.2 versions are affected by this issue. Other OpenSSL releases are out of support and have not been checked. Fixed in OpenSSL 1.1.1i (Affected 1.1.1-1.1.1h). Fixed in OpenSSL 1.0.2x (Affected 1.0.2-1.0.2w).

Remark

Vulnerability classification has been performed using the CVSS v3.1 scoring system . The CVSS environmental score is specific to each customer’s environment and should be defined by the customer to attain a final scoring.

Additional Resources

Please contact the Bosch PSIRT if you have feedback, comments, or additional information about this vulnerability at: psirt@bosch.com .

Revision History

  • 18 Dec 2020: Initial Publication