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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.0870.2 iControl REST unauthenticated remote command execution vulnerability CVE-2021-22986 29 March 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: F5 Products Publisher: F5 Networks Operating System: Network Appliance Impact/Access: Root Compromise -- Remote/Unauthenticated Execute Arbitrary Code/Commands -- Remote/Unauthenticated Create Arbitrary Files -- Remote/Unauthenticated Delete Arbitrary Files -- Remote/Unauthenticated Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2021-22986 Original Bulletin: https://support.f5.com/csp/article/K03009991 Revision History: March 29 2021: Vendor updated advisory due to issues with recent fixes March 11 2021: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- K03009991: iControl REST unauthenticated remote command execution vulnerability CVE-2021-22986 Original Publication Date: 11 Mar, 2021 Latest Publication Date: 28 Mar, 2021 Security Advisory Description The iControl REST interface has an unauthenticated remote command execution vulnerability. (CVE-2021-22986) Impact This vulnerability allows for unauthenticated attackers with network access to the iControl REST interface, through the BIG-IP management interface and self IP addresses, to execute arbitrary system commands, create or delete files, and disable services. This vulnerability can only be exploited through the control plane and cannot be exploited through the data plane. Exploitation can lead to complete system compromise. The BIG-IP system in Appliance mode is also vulnerable. 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 951705 and ID 954381 (BIG-IP) and ID 955145 (BIG-IP and BIG-IQ) 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. +-------------------+------+----------+----------+----------+------+----------+ | | |Versions |Fixes | |CVSSv3|Vulnerable| |Product |Branch|known to |introduced|Severity |score^|component | | | |be |in | |1 |or feature| | | |vulnerable| | | | | +-------------------+------+----------+----------+----------+------+----------+ | |16.x |16.0.0 - |16.0.1.1* | | | | | | |16.0.1 | | | | | | +------+----------+----------+ | | | | |15.x |15.1.0 - |15.1.2.1 | | | | | | |15.1.2 | | | | | |BIG-IP (LTM, AAM, +------+----------+----------+ | | | |Advanced WAF, AFM, |14.x |14.1.0 - |14.1.4* | | | | |Analytics, APM, | |14.1.3 | | | |iControl | |ASM, DDHD, DNS, +------+----------+----------+Critical |9.8 |REST API | |FPS, GTM, Link |13.x |13.1.0 - |13.1.3.6 | | | | |Controller, PEM, | |13.1.3 | | | | | |SSLO) +------+----------+----------+ | | | | |12.x |12.1.0 - |12.1.5.3**| | | | | | |12.1.5 | | | | | | +------+----------+----------+ | | | | |11.x |None |Not | | | | | | | |applicable| | | | +-------------------+------+----------+----------+----------+------+----------+ | |8.x |None |8.0.0 | | | | | +------+----------+----------+ | | | |BIG-IQ Centralized |7.x |7.1.0 |7.1.0.3 | | |iControl | |Management | |7.0.0 |7.0.0.2 |Critical |9.8 |REST API | | +------+----------+----------+ | | | | |6.x |6.0.0 - |None | | | | | | |6.1.0 | | | | | +-------------------+------+----------+----------+----------+------+----------+ |F5OS |1.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +-------------------+------+----------+----------+----------+------+----------+ |Traffix SDC |5.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +-------------------+------+----------+----------+----------+------+----------+ *An issue with the Traffic Management Microkernel (TMM) process has been discovered in versions 16.0.1.1 and 14.1.4. For more information, refer to K37451543: TMM vulnerability CVE-2021-23007. ^**An issue with the bigd process has been discovered in version 12.1.5.3. For more information, refer to K50524736: Bigd process memory leak after updating to BIG-IP 12.1.5.3. ^1The CVSSv3 score link takes you to a resource outside of AskF5, and it is possible that the document may be removed without our knowledge. 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 table does not list a fixed version for your software 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. Refer to K51812227: Understanding security advisory versioning. If you are using public cloud marketplaces (AWS, Azure, GCP, or Alibaba) to deploy BIG-IP Virtual Edition (VE), F5 recommends that you install the latest releases of BIG-IP versions listed in the Fixes introduced in column, subject to their availability on those marketplaces. For more information, refer to the following articles: o BIG-IP VE Supported Platforms o K84205182: BIG-IP upgrade guide | Chapter 1: Guide contents Mitigation Until it is possible to 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. 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 or TCP port 8443 on single NIC BIG-IP VE instances. If you modified the default port, ensure that you disallow access to the alternate port you configured. 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 only to 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. Indicators of compromise Important: F5 last updated this section on March 26, 2021 at 5:45 PM PacificTime. The information in this section describes evidence that F5 observed on compromised devices. F5 believes this evidence is a reliable indicator. It is important to note that exploited systems may show different indicators, and a skilled attacker may be able to remove traces of their work. It is impossible to prove a device is not compromised; when you have any uncertainty, consider the device compromised. All versions o F5 updates F5 iHealth with heuristics that flag indicators of compromise in uploaded QKView diagnostic files. Refer to K27404821: Using F5 iHealth to diagnose vulnerabilities for more information on using iHealth. o If you are unable to use iHealth to identify indicators of compromise, you may also perform the following check manually: Look for X-F5-Auth-Token doesn't have value in /var/log/restjavad.*.log . To do so, enter the following command: zgrep -e "X-F5-Auth-Token doesn't have value" /var/log/restjavad.*.log The command output may appear similar to the following example on devices that attackers attempted to compromise: /var/log/restjavad.0.log:[WARNING][2347][23 Mar 2021 08:58:30 UTC] [com.f5.rest.app.RestServerServlet] X-F5-Auth-Token doesn't have value, so skipping Note: Under limited ordinary circumstances, it is possible that log entries containing the text X-F5-Auth-Token doesn't have value may appear in /var/log/restjavad.*.log. When you see the X-F5-Auth-Token doesn't have value message, you can compare any logs found in /var/log/restjavad.*.log with those found in /var/log/audit* and /var/log/restjavad-audit.*.log that share approximately the same timestamp. Use this comparison to determine the intent and potential impact of these logs. For example, you may see the following entries in these logs: Entry in '/var/log/audit' Mar 23 00:58:30 hostname notice icrd_child[13385]: 01420002:5: AUDIT - pid=13385 user=admin folder=/Common module=(tmos)# status=[Command OK] cmd_data=run util bash -c id Entry in '/var/log/restjavad-audit.0.log' [I][2348][23 Mar 2021 08:58:30 UTC][ForwarderPassThroughWorker] {"user":"local/admin","method":"POST","uri":"http://localhost:8100/mgmt /tm/util/bash","status":200,"from":"nnn.nnn.nnn.nnn"} If the logs display any entries, this may indicate that a REST request with empty X-F5-Auth-Token value from IP address nnn.nnn.nnn.nnn invokes command run util bash -c id. You must closely examine the source IP addresses in any /var/log/restjavad-audit.*.log and /var/log/ audit* entries and compare them to IP addresses you know make legitimate REST calls against the device. o Other indicators of compromise may include unexpected modifications to any files, configurations, or running processes. F5 has iHealth heuristics designed to detect the following: Unknown processes running (Heuristic H511618) When the Configuration utility iControl REST interface has been exposed to the Internet through the management interface (H444724) When a self IP address has Port Lockdown set to Allow All (H458565) Additionally, refer to the following article: o K11438344: Considerations and guidance when you suspect a security compromise on a BIG-IP system for an overview Note: A lack of log entries or heuristic reports does not categorically indicate that a unit is not compromised. A skilled attacker can remove evidence of compromise, including log files, following successful exploitation. Supplemental Information o K02566623: Overview of F5 critical vulnerabilities (March 2021) o K04532512: Frequently asked questions for CVE-2021-22986, CVE-2021-22987, CVE-2021-22988, CVE-2021-22989, and CVE-2021-22990 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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