In December 2020, a vulnerability in OpenSSL was disclosed that can cause a NULL pointer dereference and a crash may occur leading to a possible denial of service attack when the GENERAL_NAME_cmp function is used with EDIPartyName types of names. The following vulnerability may affect the data plane of ACOS devices and is addressed in this document.
|1||CVE-2020-1971||CVSS 3.0||5.9 Medium||openssl: EDIPARTYNAME NULL pointer de-reference|
The table below indicates releases of ACOS exposed to this vulnerability and ACOS releases that address them. ACOS release families not indicated below are unaffected by these vulnerabilities.
Customers using affected ACOS releases can overcome vulnerability exposures by updating to the indicated resolved release. If the table does not list a corresponding resolved or unaffected release, then no ACOS release update is currently available.
|Releases Affected||Releases Resolved or Unaffected|
|5.2.0 – 5.2.1||5.2.1-P1|
|5.0.0 – 5.1.0-P4||5.1.0-P5, 5.2.1-P1|
|4.1.4 – 4.1.4-GR1-P5||4.1.4-GR1-P6|
Software updates that address these vulnerabilities are or will be published at the following URL: http://www.a10networks.com/support/axseries/software-downloads
The following table shares brief descriptions for the vulnerabilities addressed in this document.
|Vulnerability ID||Vulnerability 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).
|Ref #||General Link|
|1||OpenSSL Security Advisory [08 December 2020]|
|2||NIST NVD, CVE-2020-1971|
|1||January 22, 2021||
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