#threatreport #HighCompleteness
Detecting Nimbus Manticore and their sideloading infection chains | 01-06-2026
Source:
nextron-systems.com/2026/06/…
Key details below ↓
🧑💻Actors/Campaigns:
Tortoiseshell
💀Threats:
Dllsearchorder_hijacking_technique, Appdomain_hijacking_technique, Asyncrat, Junk_code_technique, Supply_chain_technique,
🎯Victims: Aerospace, Defense
🏭Industry: Aerospace, Bp_outsourcing, Financial
🌐Geo: Iran, Middle east
📚TTPs:
⚔️Tactics: 1
🛠️Technics: 0
🤖LLM extracted TTPs:`
T1027, T1027.016, T1036, T1036.003, T1071.001, T1090, T1204.002, T1564.001, T1566.002, T1574.001, ...
🧨IOCs:
- Url: 1
- File: 3
- Hash: 10
- Domain: 11
💽Software: Microsoft Visual Studio, Microsoft Word
🔢Algorithms: aes, zip
🔠Functions: TaskScheduler, CheckForUpdates
🗂️Win API: LoadLibrary, NtGlobalFlag
YARA: Found
#threatreport:
The incident described highlights operations attributed to the Iran-nexus APT group Nimbus Manticore (also known as UNC1549 or Smoke Sandstorm), which primarily targets aerospace and defense sectors in the Middle East and Europe. This group utilizes sophisticated social engineering tactics, such as impersonating a legitimate headhunter on LinkedIn to lure victims into fake recruitment processes. Their phishing attempts include well-crafted PDFs and a legitimate-looking hiring portal, which eventually lead to the deployment of malware disguised as a two-factor authentication application.
The malware employs a sideloading infection chain leveraging DLL search order hijacking and AppDomain hijacking techniques. In this instance, the malware payload is delivered in a ZIP file containing a renamed Microsoft Visual Studio component (setup.exe), which, upon execution, uses a manipulated configuration file to load an attacker-controlled assembly (TOTPGuard.dll). This setup is designed to remain inconspicuous, as the payload is signed by Microsoft and blends in with normal application behavior, thereby avoiding detection.
Throughout their campaigns, Nimbus Manticore has exhibited a pattern of increasing obfuscation within their malware. The payload analyzed featured complex code obfuscation techniques, including opaque predicates and dynamic jump calculations, aimed at hindering static analysis and reverse engineering efforts. While previous implant functionalities have remained largely consistent, the enhancements in obfuscation suggest the operators are adapting to detection methodologies and improving their evasion tactics.
The command-and-control (C2) infrastructure predominantly relies on Azure-hosted domains, which benefit from a trusted reputation and make adversarial traffic less likely to trigger alarms in environments accustomed to Azure services. Detection strategies have been proposed, emphasizing the analysis of domain age as a potential indicator of threat activity. Stricter access controls to new domains, particularly in sensitive business units, could mitigate exposure.
To counteract these tactics, organizations are encouraged to adopt comprehensive security awareness training that covers phishing beyond email and emphasizes recognizing social engineering attacks via platforms like LinkedIn. Detecting suspicious behaviors, such as anomalous sideloading techniques and unusual application configurations, is crucial for defense against the evolving strategies of threat actors like Nimbus Manticore. Overall, while the fundamental behavior of this group remains stable, their operational sophistication continues to pose substantial challenges for cybersecurity defenses.