The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued a warning about active exploitation of unencrypted persistent cookies in the F5 BIG-IP Local Traffic Manager (LTM) module by cyber threat actors. These cookies, left unencrypted, are being used for network reconnaissance, allowing attackers to gather intelligence on non-internet-facing devices within a target’s network. This tactic can enable further exploitation by identifying additional resources and vulnerabilities across the system.
CISA advises organizations using F5 BIG-IP devices to take immediate action by encrypting the persistent cookies within the HTTP profile. Encrypting these cookies helps prevent malicious actors from accessing critical network information. CISA also recommends running F5’s BIG-IP iHealth diagnostic tool, which analyzes system logs, configurations, and command outputs against known vulnerabilities, configuration errors, and best practices. The tool provides customized feedback to help organizations address potential security issues.
This advisory arrives at a time of heightened cybersecurity concerns, particularly following a joint alert from U.S. and U.K. cybersecurity agencies about Russian state-sponsored group APT29, also known as Cozy Bear or BlueBravo. This group has been linked to cyber espionage operations targeting sectors such as defense, technology, and finance. APT29 is known for its ability to maintain stealth during operations by using anonymous networks like TOR, leasing infrastructure under false identities, and exploiting publicly known vulnerabilities like CVE-2022-27924 in Zimbra Collaboration and CVE-2023-42793 in TeamCity Server.
To counter these emerging threats, CISA urges organizations to proactively secure their networks by implementing baseline security measures and scrutinizing systems that do not adhere to them. As cyber actors continually evolve their tactics to remain undetected, organizations must stay vigilant by encrypting sensitive data, monitoring network activity, and addressing misconfigurations that could leave systems vulnerable. The F5 BIG-IP vulnerability underscores the critical need for constant network hardening and regular system diagnostics to prevent malicious actors from gaining a foothold in enterprise networks.
