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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.1448.2 Appliance Mode authenticated iControl REST vulnerability CVE-2021-23015 22 July 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: BIG-IP products Publisher: F5 Networks Operating System: Network Appliance Impact/Access: Execute Arbitrary Code/Commands -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2021-23015 Reference: ESB-2021.0879 ESB-2021.0870.2 Original Bulletin: https://support.f5.com/csp/article/K74151369 Revision History: July 22 2021: Fixes introduced to 16.1.0 and 16.0.1.2 April 29 2021: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- K74151369: Appliance Mode authenticated iControl REST vulnerability CVE-2021-23015 Original Publication Date: 29 Apr, 2021 Latest Publication Date: 22 Jul, 2021 Security Advisory Description When running in Appliance Mode, an authenticated user assigned the 'Administrator' role may be able to bypass Appliance Mode restrictions utilizing undisclosed iControl REST endpoints. (CVE-2021-23015) Note: This vulnerability is unrelated to the vulnerability described in the following article: K03009991: iControl REST unauthenticated remote command execution vulnerability CVE-2021-22986. Impact In Appliance Mode, an authenticated user with valid user credentials assigned the Administrator role may be able to bypass appliance mode restrictions and run arbitrary commands. This is a control plane issue; there is no data plane exposure. Appliance Mode is enforced by a specific license or may be enabled or disabled for individual Virtual Clustered Multiprocessing (vCMP) guest instances. For information on Appliance mode, refer to: K12815: Overview of Appliance mode. Note: If you believe your system may have been compromised, refer to K11438344: Considerations and guidance when you suspect a security compromise on a BIG-IP system. Security Advisory Status F5 Product Development has assigned ID 959121, ID 1003105, and ID 1003557 (BIG-IP) 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 following table 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^1 |in | |2 |feature | +------------+------+-------------+----------+-----------+------+-------------+ | | | |16.1.0 | | | | | |16.x |16.0.0 - |16.0.1.2 | | | | | | |16.0.1 | | | | | | +------+-------------+----------+ | | | | |15.x |15.1.0 - |15.1.3 | | | | | | |15.1.2 | | | | | | +------+-------------+----------+High - | | | | |14.x |14.1.0 - |14.1.4.2 |Appliance | | | |BIG-IP (all | |14.1.4 | |Mode Only^3|8.7 |iControl REST| |modules) +------+-------------+----------+ | | | | |13.x |13.1.0.8 - |13.1.4 | | | | | | |13.1.3 | | | | | | +------+-------------+----------+ | | | | |12.x |None |Not | | | | | | | |applicable| | | | | +------+-------------+----------+ | | | | |11.x |None |Not | | | | | | | |applicable| | | | +------------+------+-------------+----------+-----------+------+-------------+ | |8.x |None |Not | | | | | | | |applicable| | | | |BIG-IQ +------+-------------+----------+ | | | |Centralized |7.x |None |Not |Not |None |None | |Management | | |applicable|vulnerable | | | | +------+-------------+----------+ | | | | |6.x |None |Not | | | | | | | |applicable| | | | +------------+------+-------------+----------+-----------+------+-------------+ |F5OS |1.x |None |Not |Not |None |None | | | | |applicable|vulnerable | | | +------------+------+-------------+----------+-----------+------+-------------+ |Traffix SDC |5.x |None |Not |Not |None |None | | | | |applicable|vulnerable | | | +------------+------+-------------+----------+-----------+------+-------------+ ^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. ^3This vulnerability exists for only the limited number of customers using Appliance Mode. For information on Appliance mode, refer to: K12815: Overview of Appliance mode. 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 F5 suggests that you audit users assigned the Administrator role in any installations and limit the number of users assigned that role. As the vulnerability is exposed only to users assigned the Administrator role, consider reducing privileges, where possible, to Resource Administrator or lower. Until you can install a fixed version, you can use the following sections as temporary mitigations. These mitigations restrict access to iControl REST to only trusted networks or devices, thereby limiting the attack surface. Note that the attack must be carried out by an attacker who holds valid credentials to a highly privileged administrative account. Therefore, restricting access may still leave the device exposed to the risk of a malicious insider or lateral movement from another compromised device within the trusted range. o Block iControl REST access through the self IP address o Block iControl REST access through the management interface Block iControl REST access through the self IP address You can block all access to the iControl REST interface of your BIG-IP system through self IP addresses. To do so, you can change the Port Lockdown setting to Allow None for each self IP address in the system. If you must open any ports, you should use the Allow Custom option, taking care to disallow access to iControl REST. By default, iControl REST listens on TCP port 443. Alternatively, you can configure a custom port. Note: Performing this action prevents all access to the Configuration utility and iControl REST 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 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 on your self IP addresses and want to restrict access to specific IP ranges, you may consider using the packet filtering functionality built in to 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 iControl REST access through the management interface To mitigate this vulnerability for affected F5 products, you should restrict management access to only trusted users and devices over a secure network. For more information about securing access to BIG-IP systems, refer to the following articles: o K13092: Overview of securing access to the BIG-IP system o K46122561: Restricting access to the management interface using network firewall rules o K69354049: Restricting access to the BIG-IP management interface for Configuration Utility and iControl REST services using iptables Note: Restricting access to the management interface by IP address in httpd is not a viable mitigation for this issue. Acknowledgements F5 acknowledges the following Security Researchers for bringing this issue to our attention and following the highest standards of coordinated disclosure: o William Vu of Rapid7 o HTTPVoid (Rahul Maini & Harsh Jaiswal) o The Unisys Security Incident Response Team 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 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. 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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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