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US Cyber Command urges F5 customers to fix critical flaw in BIG

criticalVulnerabilityimportance 60CVE-2020-5902

Vulnerabilities mentionedAll →

CVEVulnerabilityCVSSEPSSFlagsAffectedExposurePublished
CVE-2020-5902
Unauthenticated RCE via path traversal in F5 BIG-IP TMUI

CVE-2020-5902 is a critical, unauthenticated remote code execution flaw in the F5 BIG-IP Traffic Management User Interface (TMUI), the appliance's web management console, rooted in a directory/path traversal issue (CWE-22) in undisclosed TMUI pages. It is triggered by sending crafted HTTP(S) requests to the management interface — classically path-traversal URLs beneath the TMUI application on the management port — which lets an attacker bypass authentication, read or delete arbitrary files, and execute commands without credentials. Successful exploitation yields full control of the BIG-IP system, which attackers can use to pivot into networks the appliance fronts, maintain persistence, and deploy ransomware. Any organization running an affected F5 BIG-IP appliance or virtual edition whose TMUI is reachable, or whose management network can be reached, is exposed; F5's installed base spans large enterprises and service providers, so the footprint is broad. Exploitation is confirmed in the wild: the flaw was mass-scanned and exploited within days of its July 2020 disclosure, it is listed in CISA KEV with known ransomware use, and EPSS assigns a ~100% probability of exploitation within 30 days.

Do: Patch immediately using F5's advisory K52145254 — upgrade BIG-IP to a fixed release per the vendor's version matrix, since CISA's required action is applying vendor updates. Until patched, restrict TMUI/management-interface access to trusted source IPs or a VPN (or disable TMUI if unused) and apply F5's published interim workaround. Because ransomware use is confirmed, hunt for indicators of compromise on both patched and unpatched appliances (unexpected files, webshells, modified login pages, new accounts or scheduled tasks) before treating systems as clean.

9.8100% KEV ransomware PoC ×8
  • F5 BIG-IP
mass≈100,000–300,000 internet-exposed BIG-IP TMUI endpoints, with a far larger internal installed base
Full article430 words · extracted from securityaffairs.com · click to collapse

F5 Networks has published a security advisory warning customers to patch a critical flaw in BIG-IP product that is very likely to be exploited.

F5 Networks has addressed a critical remote code execution (RCE) vulnerability, tracked as CVE-2020-5902, that resides in undisclosed pages of Traffic Management User Interface (TMUI) of the BIG-IP product.

“This vulnerability allows for unauthenticated attackers, or authenticated users, with network access to the TMUI, through the BIG-IP management port and/or Self IPs, to execute arbitrary system commands, create or delete files, disable services, and/or execute arbitrary Java code.” reads the advisory published by F5. “This vulnerability may result in complete system compromise. The BIG-IP system in Appliance mode is also vulnerable. This issue is not exposed on the data plane; only the control plane is affected.”

The BIG-IP product is an application delivery controller (ADC), it is used by government agencies and major business, including banks, services providers and IT giants like Facebook, Microsoft and Oracle.

F5 Networks says the BIG-IP devices are used on the networks of 48 companies included in the Fortune 50 list.

US Cyber Command is urging organizations using the F5 product to immediately patch their installs.

URGENT: Patching CVE-2020-5902 and 5903 should not be postponed over the weekend. Remediate immediately. https://t.co/UBKECuN7Vv

— USCYBERCOM Cybersecurity Alert (@CNMF_CyberAlert) July 3, 2020

The CVE-2020-5902 flaw in BIG-IP was privately reported to F5 by Mikhail Klyuchnikov from Positive Technologies.

“Positive Technologies expert Mikhail Klyuchnikov has discovered a vulnerability in the configuration interface of the BIG-IP application delivery controller (ADC) used by some of the world’s biggest companies.” reads the advisory published by Positive Technologies. “Attackers can run commands as an unauthorized user and completely compromise a system, including interception of controller application traffic. The vulnerability can be exploited remotely.”

The vulnerability could be exploited by attackers to gain access to the TMUI component to execute arbitrary system commands, disable services, execute arbitrary Java code, and create or delete files, and potentially take over the BIG-IP device

The CVE-2020-5902 vulnerability received a CVSS score of 10, this means that is quite easy to exploit. The issue could be exploited by sending a specifically crafted HTTP request to the server hosting the Traffic Management User Interface (TMUI) utility for BIG-IP configuration.

Searching for BIG-IP devices connected online using the Shodan search engine we can find around 8,400 installs, most of in the US (40%), followed by China (16%) and Taiwan (3%).

Experts expect attacks exploiting this vulnerability will begin soon.

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Pierluigi Paganini

(SecurityAffairs – hacking, F5 Networks)

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