Risk actors have been exploiting the newly disclosed zero-day flaw in Palo Alto Networks PAN-OS software program courting again to March 26, 2024, almost three weeks earlier than it got here to gentle yesterday.
The community safety firm’s Unit 42 division is monitoring the exercise underneath the identify Operation MidnightEclipse, attributing it because the work of a single menace actor of unknown provenance.
The safety vulnerability, tracked as CVE-2024-3400 (CVSS rating: 10.0), is a command injection flaw that permits unauthenticated attackers to execute arbitrary code with root privileges on the firewall.
It is price noting that the difficulty is relevant solely to PAN-OS 10.2, PAN-OS 11.0, and PAN-OS 11.1 firewall configurations which have GlobalProtect gateway and gadget telemetry enabled.
Operation MidnightEclipse entails the exploitation of the flaw to create a cron job that runs each minute to fetch instructions hosted on an exterior server (“172.233.228[.]93/coverage” or “172.233.228[.]93/patch”), that are then executed utilizing the bash shell.
The attackers are mentioned to have manually managed an entry management checklist (ACL) for the command-and-control (C2) server to make sure that it could solely be accessed from the gadget speaking with it.
Whereas the precise nature of the command is unknown, it is suspected that the URL serves as a supply automobile for a Python-based backdoor on the firewall that Volexity – which found in-the-wild exploitation of CVE-2024-3400 on April 10, 2024 – is monitoring as UPSTYLE and is hosted on a unique server (“144.172.79[.]92” and “nhdata.s3-us-west-2.amazonaws[.]com”).
The Python file is designed to write down and launch one other Python script (“system.pth”), which subsequently decodes and runs the embedded backdoor part that is liable for executing the menace actor’s instructions in a file referred to as “sslvpn_ngx_error.log.” The outcomes of the operation are written to a separate file named “bootstrap.min.css.”
Probably the most attention-grabbing facet of the assault chain is that each the information used to extract the instructions and write the outcomes are professional information related to the firewall –
- /var/log/pan/sslvpn_ngx_error.log
- /var/appweb/sslvpndocs/global-protect/portal/css/bootstrap.min.css
As for the way the instructions are written to the online server error log, the menace actor forges specifically crafted community requests to a non-existent internet web page containing a selected sample. The backdoor then parses the log file and searches for the road matching the identical common expression (“img[([a-zA-Z0-9+/=]+)]”) to decode and run the command inside it.
“The script will then create one other thread that runs a perform referred to as restore,” Unit 42 mentioned. “The restore perform takes the unique content material of the bootstrap.min.css file, in addition to the unique entry and modified instances, sleeps for 15 seconds and writes the unique contents again to the file and units the entry and modified instances to their originals.”
The principle purpose seems to be to keep away from leaving traces of the command outputs, necessitating that the outcomes are exfiltrated inside 15 seconds earlier than the file is overwritten.
Volexity, in its personal evaluation, mentioned it noticed the menace actor remotely exploiting the firewall to create a reverse shell, obtain further tooling, pivot into inner networks, and finally exfiltrate knowledge. The precise scale of the marketing campaign is presently unclear. The adversary has been assigned the moniker UTA0218 by the corporate.
“The tradecraft and velocity employed by the attacker suggests a extremely succesful menace actor with a transparent playbook of what to entry to additional their targets,” the American cybersecurity agency mentioned.
“UTA0218’s preliminary targets have been aimed toward grabbing the area backup DPAPI keys and focusing on energetic listing credentials by acquiring the NTDS.DIT file. They additional focused person workstations to steal saved cookies and login knowledge, together with the customers’ DPAPI keys.”
Organizations are really useful to search for indicators of lateral motion internally from their Palo Alto Networks GlobalProtect firewall gadget.
The event has additionally prompted the U.S. Cybersecurity and Infrastructure Safety Company (CISA) so as to add the flaw to its Identified Exploited Vulnerabilities (KEV) catalog, requiring federal companies to use the patches by April 19 to mitigate potential threats. Palo Alto Networks is predicted to launch fixes for the flaw no later than April 14.
“Focusing on edge gadgets stays a preferred vector of assault for succesful menace actors who’ve the time and sources to take a position into researching new vulnerabilities,” Volexity mentioned.
“It’s extremely seemingly UTA0218 is a state-backed menace actor based mostly on the sources required to develop and exploit a vulnerability of this nature, the kind of victims focused by this actor, and the capabilities displayed to put in the Python backdoor and additional entry sufferer networks.”