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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.3285.2 OpenSSL vulnerability CVE-2021-3712 28 October 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: F5 BIG-IP Products F5 BIG-IQ Centralized Management F5OS F5 Traffix SDC Publisher: F5 Networks Operating System: Network Appliance Impact/Access: Denial of Service -- Remote/Unauthenticated Access Confidential Data -- Remote/Unauthenticated Resolution: None CVE Names: CVE-2021-3712 Reference: ESB-2021.3261 ESB-2021.3201 ESB-2021.2895 ESB-2021.2891 Original Bulletin: https://support.f5.com/csp/article/K19559038 Revision History: October 28 2021: Vendor increased severity rating and issued further mitigation advice October 5 2021: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- K19559038: OpenSSL vulnerability CVE-2021-3712 Original Publication Date: 02 Oct, 2021 Latest Publication Date: 28 Oct, 2021 Security Advisory Description ASN.1 strings are represented internally within OpenSSL as an ASN1_STRING structure which contains a buffer holding the string data and a field holding the buffer length. This contrasts with normal C strings which are repesented as a buffer for the string data which is terminated with a NUL (0) byte. Although not a strict requirement, ASN.1 strings that are parsed using OpenSSL's own "d2i" functions (and other similar parsing functions) as well as any string whose value has been set with the ASN1_STRING_set() function will additionally NUL terminate the byte array in the ASN1_STRING structure. However, it is possible for applications to directly construct valid ASN1_STRING structures which do not NUL terminate the byte array by directly setting the "data" and "length" fields in the ASN1_STRING array. This can also happen by using the ASN1_STRING_set0() function. Numerous OpenSSL functions that print ASN.1 data have been found to assume that the ASN1_STRING byte array will be NUL terminated, even though this is not guaranteed for strings that have been directly constructed. Where an application requests an ASN.1 structure to be printed, and where that ASN.1 structure contains ASN1_STRINGs that have been directly constructed by the application without NUL terminating the "data" field, then a read buffer overrun can occur. The same thing can also occur during name constraints processing of certificates (for example if a certificate has been directly constructed by the application instead of loading it via the OpenSSL parsing functions, and the certificate contains non NUL terminated ASN1_STRING structures). It can also occur in the X509_get1_email(), X509_REQ_get1_email() and X509_get1_ocsp() functions. If a malicious actor can cause an application to directly construct an ASN1_STRING and then process it through one of the affected OpenSSL functions then this issue could be hit. This might result in a crash (causing a Denial of Service attack). It could also result in the disclosure of private memory contents (such as private keys, or sensitive plaintext). Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected 1.0.2-1.0.2y). (CVE-2021-3712) Impact A remote attacker can exploit the vulnerability by triggering an application to create an ASN1_STRING and process it with an affected OpenSSL function to access restricted information or cause a denial-of-service (DoS). Security Advisory Status F5 Product Development has assigned ID 1043281 (BIG-IP), ID 1043973 (BIG-IP iRulesLX/iAppsLX and BIG-IQ), ID 1048885 (BIG-IP APM Oracle Access Manager), ID 1046365 (F5 Access), ID 1044545 (BIG-IP Edge Client), ID 1044645 (F5OS), SDC-1338 (Traffix SDC 5.1.x), and SDC-1341 (Traffix SDC 5.2.x) to this vulnerability. To determine if your product and version have been evaluated for this vulnerability, refer to the Applies to (see versions) box. To determine if your release is known to be vulnerable, the components or features that are affected by the vulnerability, and for information about releases, point releases, or hotfixes that address the vulnerability, refer to the following table. For more information about security advisory versioning, refer to K51812227: Understanding security advisory versioning. Note: After a fix is introduced for a given minor branch, that fix applies to all subsequent maintenance and point releases for that branch, and no additional fixes for that branch will be listed in the table. For example, when a fix is introduced in 14.1.2.3, the fix also applies to 14.1.2.4, and all later 14.1.x releases (14.1.3.x., 14.1.4.x). For more information, refer to K51812227: Understanding security advisory versioning. Additionally, software versions preceding those listed in the Applies to (see versions) box of this article have reached the End of Technical Support (EoTS) phase of their lifecycle and are no longer evaluated for security issues. For more information, refer to the Security hotfixes section of K4602: Overview of the F5 security vulnerability response policy. +-----------+------+-----------+----------+--------+------+-------------------+ | | |Versions |Fixes | |CVSSv3|Vulnerable | |Product |Branch|known to be|introduced|Severity|score^|component or | | | |vulnerable^|in | |2 |feature | | | |1 | | | | | +-----------+------+-----------+----------+--------+------+-------------------+ | |16.x |16.0.0 - |None | | | | | | |16.1.1^3 | | | | | | +------+-----------+----------+ | | | | |15.x |15.1.0 - |None | | | | | | |15.1.4^3 | | | | | | +------+-----------+----------+ | | | | |14.x |14.1.0 - |None | | | | |BIG-IP | |14.1.4^3 | | | |OpenSSL, Oracle | |(APM)^4 +------+-----------+----------+High |7.4 |Access Manager | | |13.x |13.1.0 - |None | | |(OAM) SDK | | | |13.1.4^3 | | | | | | +------+-----------+----------+ | | | | |12.x |12.1.0 - |None | | | | | | |12.1.6 | | | | | | +------+-----------+----------+ | | | | |11.x |11.6.1 - |None | | | | | | |11.6.5 | | | | | +-----------+------+-----------+----------+--------+------+-------------------+ | |16.x |16.0.0 - |None | | | | | | |16.1.0 | | | | | | +------+-----------+----------+ | | | | |15.x |15.1.0 - |None | | | | | | |15.1.4 | | | | | | +------+-----------+----------+ | | | | |14.x |14.1.0 - |None | | | | |BIG-IP (all| |14.1.4 | | | | | |other +------+-----------+----------+High |7.4 |OpenSSL | |modules)^4 |13.x |13.1.0 - |None | | | | | | |13.1.4 | | | | | | +------+-----------+----------+ | | | | |12.x |12.1.0 - |None | | | | | | |12.1.6 | | | | | | +------+-----------+----------+ | | | | |11.x |11.6.1 - |None | | | | | | |11.6.5 | | | | | +-----------+------+-----------+----------+--------+------+-------------------+ | |16.x |16.0.0 - |None | | | | | | |16.1.0 | | | | | | +------+-----------+----------+ | | | | |15.x |15.1.0 - |None | | | | | | |15.1.4 | | | | | | +------+-----------+----------+ | | | | |14.x |14.1.0 - |None | | | | |BIG-IP | |14.1.4 | | | | | |(iRulesLX/ +------+-----------+----------+High |7.4 |OpenSSL | |iAppsLX)^4 |13.x |13.1.0 - |None | | | | | | |13.1.4 | | | | | | +------+-----------+----------+ | | | | |12.x |12.1.0 - |None | | | | | | |12.1.6 | | | | | | +------+-----------+----------+ | | | | |11.x |None |Not | | | | | | | |applicable| | | | +-----------+------+-----------+----------+--------+------+-------------------+ | | | | | | |OpenSSL, BIG-IP | |BIG-IP APM | |7.2.1 | | | |Edge Client | |Clients |7.x |7.1.5 - |None |High |7.4 |TunnelServer, and | | | |7.1.9 | | | |F5 Access | | | | | | | |ShareExtension | +-----------+------+-----------+----------+--------+------+-------------------+ | |8.x |8.0.0 - |None | | | | | | |8.1.0 | | | | | |BIG-IQ +------+-----------+----------+ | | | |Centralized|7.x |7.0.0 - |None |High |7.4 |OpenSSL | |Management | |7.1.0 | | | | | | +------+-----------+----------+ | | | | |6.x |6.1.0 |None | | | | +-----------+------+-----------+----------+--------+------+-------------------+ | | |1.2.0 - | | | | | |F5OS |1.x |1.2.1 |None |High |7.4 |OpenSSL | | | |1.1.0 - | | | | | | | |1.1.4 | | | | | +-----------+------+-----------+----------+--------+------+-------------------+ |Traffix SDC|5.x |5.2.0 |None |High |7.4 |OpenSSL | | | |5.1.0 | | | | | +-----------+------+-----------+----------+--------+------+-------------------+ ^1F5 evaluates only software versions that have not yet reached the End of Technical Support (EoTS) phase of their lifecycle. ^2The CVSSv3 score link takes you to a resource outside of AskF5, and it is possible that the document may be removed without our knowledge. ^3In BIG-IP 13.1.0 and later, you can update APM client components independently from BIG-IP software. To address this vulnerability separately for APM client components, customers running BIG-IP 13.1.0 and later can download and install an APM Clients version listed in the Fixes introduced in column, and then redeploy the BIG-IP Edge Client to end users. If the Fixes introduced in column does not list a version for your branch, then no update candidate currently exists. ^4TMM is not affected by this vulnerability. Recommended Actions If you are running a version listed in the Versions known to be vulnerable column, you can eliminate this vulnerability by installing a version listed in the Fixes introduced in column. If the Fixes introduced in column does not list a version for your branch, then no update candidate currently exists for that branch and F5 recommends upgrading to a version with the fix (refer to the table). If the Fixes introduced in column lists a version prior to the one you are running, in the same branch, then your version should have the fix. Mitigation To mitigate this vulnerability, you should permit management access to F5 products only over a secure network and restrict command line access for affected systems to trusted users. For more information about BIG-IP and BIG-IQ systems, refer to the following section. BIG-IP and BIG-IQ Until it is possible to install a fixed version, you can use the following sections as temporary mitigations. These mitigations restrict access to the BIG-IP or BIG-IQ Configuration utility and command line through SSH to only trusted networks or devices, thereby limiting the attack surface. o Block Configuration utility and SSH access through self IP addresses o Block Configuration utility and SSH access through the management interface Block Configuration utility and SSH access through self IP addresses You can block all access to the Configuration utility and SSH of your BIG-IP or BIG-IQ system using self IP addresses. To do so, you can change the Port Lockdown setting to Allow None for each self IP address on the system. If you must open any ports, you should use the Allow Custom option, taking care to block access to the Configuration utility and SSH. By default, the Configuration utility listens on TCP port 443 and the SSH service listens on TCP port 22. If you modified the default port, ensure that you block access to the alternate port you configured. Note: Performing this action prevents all access to the Configuration utility, iControl REST, and to SSH using the self IP address. These changes may also impact other services, including breaking high availability (HA) configurations. Before you make changes to the configuration of your self IP addresses, F5 strongly recommends that you refer to the following articles: o K17333: Overview of port lockdown behavior (12.x - 16.x) o K39403510: Managing the port lockdown configuration on the BIG-IQ system o K13092: Overview of securing access to the BIG-IP system o K31003634: The Configuration utility of the Single-NIC BIG-IP Virtual Edition now defaults to TCP port 8443 o K51358480: The single-NIC BIG-IP VE may erroneously revert to the default management httpd port after a configuration reload If you must expose port 443 or port 22 on your self IP addresses and want to restrict access to specific IP ranges, you may consider using the packet filtering functionality built into the BIG-IP system. For more information, refer to the following article: o K13383: Configuring CIDR Network Addresses for the BIG-IP packet filter Block Configuration utility and SSH access through the management interface To mitigate this vulnerability for affected F5 products, you should restrict management access to only trusted users and devices to F5 products over a secure network. For more information about securing access to BIG-IP and BIG-IQ systems, refer to the following articles: o K13309: Restricting access to the Configuration utility by source IP address (11.x - 16.x) o K31401771: Restricting access to the BIG-IQ or F5 iWorkflow user interface by source IP address o K13092: Overview of securing access to the BIG-IP system o K46122561: Restricting access to the BIG-IP management interface using network firewall rules o K92748202: Restricting access to the BIG-IQ management interface using network firewall rules Supplemental Information o K41942608: Overview of security advisory articles o K4602: Overview of the F5 security vulnerability response policy o K4918: Overview of the F5 critical issue hotfix policy o K8986: F5 software lifecycle policy o K9502: BIG-IP hotfix and point release matrix o K13123: Managing BIG-IP product hotfixes (11.x - 16.x) o K15106: Managing BIG-IQ product hotfixes o K15113: BIG-IQ hotfix and point release matrix o K48955220: Installing an OPSWAT Endpoint Security update on BIG-IP APM systems (11.4.x and later) o K167: Downloading software and firmware from F5 o K9970: Subscribing to email notifications regarding F5 products o K9957: Creating a custom RSS feed to view new and updated documents - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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