Hackers Deploy Python Backdoor in Palo Alto Zero-Working day Attack

Apr 13, 2024Newsroom

Risk actors have been exploiting the freshly disclosed zero-day flaw in Palo Alto Networks PAN-OS application courting again to March 26, 2024, nearly 3 weeks right before it arrived to light yesterday.

The network security firm’s Device 42 division is tracking the action less than the identify Procedure MidnightEclipse, attributing it as the function of a single threat actor of unknown provenance.

The stability vulnerability, tracked as CVE-2024-3400 (CVSS rating: 10.), is a command injection flaw that enables unauthenticated attackers to execute arbitrary code with root privileges on the firewall.

It truly is really worth noting that the problem is applicable only to PAN-OS 10.2, PAN-OS 11., and PAN-OS 11.1 firewall configurations that have GlobalProtect gateway and unit telemetry enabled.

Procedure MidnightEclipse entails the exploitation of the flaw to develop a cron job that operates each individual moment to fetch commands hosted on an exterior server (“172.233.228[.]93/coverage” or “172.233.228[.]93/patch”), which are then executed making use of the bash shell.

The attackers are mentioned to have manually managed an entry regulate record (ACL) for the command-and-handle (C2) server to make sure that it can only be accessed from the product communicating with it.


Whilst the precise mother nature of the command is unfamiliar, it really is suspected that the URL serves as a shipping and delivery vehicle for a Python-based backdoor on the firewall that Volexity – which uncovered in-the-wild exploitation of CVE-2024-3400 on April 10, 2024 – is tracking as UPSTYLE and is hosted on a various server (“144.172.79[.]92” and “nhdata.s3-us-west-2.amazonaws[.]com”).

The Python file is intended to compose and launch another Python script (“system.pth”), which subsequently decodes and runs the embedded backdoor ingredient that’s responsible for executing the threat actor’s commands in a file termed “sslvpn_ngx_error.log.” The benefits of the operation are created to a separate file named “bootstrap.min.css.”

The most exciting factor of the assault chain is that each the data files employed to extract the commands and publish the outcomes are legit data files involved with the firewall –

  • /var/log/pan/sslvpn_ngx_error.log
  • /var/appweb/sslvpndocs/world-protect/portal/css/bootstrap.min.css

As for how the commands are prepared to the world wide web server mistake log, the risk actor forges specially crafted network requests to a non-existent website site containing a precise pattern. The backdoor then parses the log file and queries for the line matching the very same standard expression (“img[([a-zA-Z0-9+/=]+)]”) to decode and operate the command within it.

“The script will then create an additional thread that operates a perform called restore,” Unit 42 explained. “The restore purpose usually takes the first content material of the bootstrap.min.css file, as well as the primary entry and modified moments, sleeps for 15 seconds and writes the first contents again to the file and sets the accessibility and modified situations to their originals.”

Palo Alto Zero-Day Attacks

The key purpose appears to be to stay clear of leaving traces of the command outputs, necessitating that the outcomes are exfiltrated inside of 15 seconds ahead of the file is overwritten.

Volexity, in its personal analysis, said it observed the risk actor remotely exploiting the firewall to develop a reverse shell, obtain added tooling, pivot into inner networks, and finally exfiltrate details. The specific scale of the marketing campaign is presently unclear. The adversary has been assigned the moniker UTA0218 by the firm.


“The tradecraft and pace used by the attacker implies a remarkably capable danger actor with a very clear playbook of what to access to further more their objectives,” the American cybersecurity business stated.

“UTA0218’s original goals have been aimed at grabbing the domain backup DPAPI keys and concentrating on energetic listing qualifications by getting the NTDS.DIT file. They more targeted user workstations to steal saved cookies and login information, alongside with the users’ DPAPI keys.”

Organizations are encouraged to appear for signals of lateral movement internally from their Palo Alto Networks GlobalProtect firewall product.

The growth has also prompted the U.S. Cybersecurity and Infrastructure Stability Agency (CISA) to add the flaw to its Known Exploited Vulnerabilities (KEV) catalog, requiring federal businesses to use the patches by April 19 to mitigate potential threats. Palo Alto Networks is predicted to launch fixes for the flaw no afterwards than April 14.

“Targeting edge gadgets stays a well-liked vector of attack for capable menace actors who have the time and resources to devote into investigating new vulnerabilities,” Volexity mentioned.

“It is really very likely UTA0218 is a condition-backed menace actor primarily based on the methods essential to create and exploit a vulnerability of this character, the variety of victims focused by this actor, and the capabilities displayed to install the Python backdoor and further access target networks.”

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