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Malware Analysis Report: UMBRELLA STAND - Malware targeting Fortinet devices

Medium
Published: Mon Jun 23 2025 (06/23/2025, 11:34:33 UTC)
Source: AlienVault OTX General

Description

UMBRELLA STAND is a sophisticated malware targeting FortiGate 100D series firewalls produced by Fortinet. It contains remote shell execution functionality, configurable beacon frequency, and AES-encrypted C2 communications. The malware uses fake TLS on port 443 to beacon to its C2 server and has the ability to run shell commands. It employs various defense evasion techniques such as hidden folders, generic filenames, and string encryption. UMBRELLA STAND also has persistence mechanisms through reboot hooking and ldpreload. Associated tooling includes BusyBox, nbtscan, tcpdump, and openLDAP. The malware demonstrates operational security considerations and shares similarities with previously reported COATHANGER malware.

AI-Powered Analysis

AILast updated: 06/24/2025, 14:25:00 UTC

Technical Analysis

UMBRELLA STAND is a sophisticated malware strain specifically targeting Fortinet FortiGate 100D series firewalls. This malware is designed to compromise network perimeter security devices, enabling attackers to gain remote shell access to the affected firewall. It features configurable beaconing intervals to communicate with its command and control (C2) servers over port 443 using fake TLS traffic, which helps it blend in with legitimate encrypted traffic and evade network detection. The C2 communications are encrypted using AES, adding a layer of confidentiality to the attacker’s command channel. UMBRELLA STAND employs multiple defense evasion techniques, including the use of hidden folders and generic filenames to avoid detection by administrators and security tools, as well as string encryption to hinder static analysis. For persistence, it hooks into the system reboot process and uses the ldpreload mechanism to maintain its presence even after device restarts. The malware also leverages legitimate tools such as BusyBox, nbtscan, tcpdump, and openLDAP to facilitate network reconnaissance and data exfiltration, indicating a high level of operational security and sophistication. The malware shares similarities with the previously documented COATHANGER malware, suggesting possible shared development lineage or adversary tactics. Notably, there are no known exploits in the wild targeting this malware yet, and no specific affected firmware versions have been identified, which may indicate either a targeted or emerging threat. The malware’s ability to execute arbitrary shell commands remotely on a firewall device poses a significant risk to network integrity and confidentiality.

Potential Impact

For European organizations, the compromise of FortiGate 100D firewalls by UMBRELLA STAND could have severe consequences. FortiGate devices are widely deployed across various sectors including government, finance, telecommunications, and critical infrastructure within Europe. Successful exploitation would allow attackers to bypass perimeter defenses, intercept or manipulate network traffic, and potentially pivot into internal networks. This could lead to data breaches involving sensitive personal data protected under GDPR, disruption of critical services, and loss of trust in organizational security. The malware’s stealthy communication and persistence mechanisms make detection and remediation challenging, increasing the risk of prolonged undetected compromise. Additionally, the use of legitimate tools for reconnaissance and exfiltration complicates incident response efforts. Given the strategic importance of Fortinet firewalls in securing enterprise and public sector networks, this malware could facilitate espionage, sabotage, or ransomware deployment, especially in sectors critical to European economies and national security.

Mitigation Recommendations

1. Conduct immediate audits of FortiGate 100D devices for indicators of compromise such as unusual processes, hidden directories, or unexpected network traffic on port 443. 2. Implement network traffic analysis focusing on detecting anomalous TLS sessions that do not conform to expected Fortinet management or VPN traffic patterns. 3. Employ endpoint detection and response (EDR) tools capable of identifying persistence mechanisms like ldpreload hooks and reboot hooking on firewall devices. 4. Restrict administrative access to FortiGate devices using multi-factor authentication and limit management interfaces to trusted networks only. 5. Regularly update Fortinet firmware and software, even though no specific patches are currently linked to this malware, to reduce exposure to known vulnerabilities. 6. Monitor for the presence of auxiliary tools such as BusyBox, nbtscan, tcpdump, and openLDAP on firewall devices, as their unauthorized use may indicate compromise. 7. Establish strict logging and alerting for shell command executions on FortiGate devices. 8. Collaborate with Fortinet support and cybersecurity information sharing organizations to receive timely threat intelligence updates. 9. Consider network segmentation to isolate critical firewall infrastructure and reduce lateral movement opportunities. 10. Conduct staff training to recognize signs of firewall compromise and ensure incident response plans include scenarios involving firewall malware.

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Technical Details

Author
AlienVault
Tlp
white
References
["https://www.ncsc.gov.uk/static-assets/documents/malware-analysis-reports/umbrella-stand/ncsc-mar-umbrella_stand.pdf"]
Adversary
null
Pulse Id
68593bc9c284f1baf4623782
Threat Score
null

Indicators of Compromise

Hash

ValueDescriptionCopy
hash43f398bfe3eecd5584ebf3321000c3cd
hash50664a15bce874e53cdc99c220a10aab
hash586856b41eb0f101924caeead5aeb4f0
hash615521d36644d11f53e17805a1422f29
hash6bdfac0500e164de8c6bbd13e05b3968
hash79c8db07491b9049921b060ee059877a
hash821b1158aa87a055030c99b93026485a
hashc8c20c56c950eb291ce7902bf1c28485
hashd07a6070e4cee1716fc882bc1d51b7bc
hashff82ea16717c6fa9fc8c07ae2de09c5f
hash28ff882baa02c646bcdddffacb75923490a3dcf7
hash3294257f9085a727a7723885e8431e8a036d3082
hash3a7d09c9ce2ff7f6026cda4a7f80945ee0952c95
hash73e2ae5b03e20eaa4e2cafb2000d57321bfa0b5f
hash7931678cdd0d143ca98c18a00b8d237583fa8d93
hash8632487a9f19223b20d34c082a3077ca6ac6eac4
hash99dde2df0b8b31fce5807d710c1b8d9018a56f58
hashc2a463d5091efb2be590fbfa5dba5a821d5625cf
hashc8183d12c2070cf04cd03f080904ed1312a56911
hashd21e46856ffb344ed06a461efb554e5a490a9e3e
hash190293440fce95f45eb8bf5d40334b41dd68c79578d06fe9b34670298daea7f3
hash38801caae26916367dd6cf6e8c55e50ed62526fe242cd0343dfe80a70564c28a
hash591d60c1d356da827a26f4141fa431d3663af91746d5371014695b1c89bac2b2
hash65f1e17f7fa2e2fd9c57265f390484a7428c192f59ee41fc7c0d8386ea3b811a
hash6a3abc19f324a475d4ce01fcc69797fc90e1a47970ed90e9cb01f540f3000b4e
hash881998c9864d2c7fe35f9b8071dbcf84386cb15da77e6f6a086cf605a4dd7823
hash8bacd5df99476328321a7e8e2fc0124c20f7a7ebf3e8f151c050387038515b70
hasha64b41e98e3e1066f41fbff5d4f99f6d34b792d35fe2be7e5d9fa8f3f8b93739
hashd1d5f502e2039b20269b562bbc1e5622a73bbecad54cb25ae5eaa7a91504e70e
hashd3b88b7f640e478d8d875e12b4561e8c794909e4954aebbc6fd1f5e79f381648

Ip

ValueDescriptionCopy
ip89.44.194.32

Threat ID: 685ab4fdaf41c610cd95c1a2

Added to database: 6/24/2025, 2:23:57 PM

Last enriched: 6/24/2025, 2:25:00 PM

Last updated: 8/12/2025, 3:47:28 AM

Views: 34

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