Full Report
2025-05-28 • Rapid7 • Anna Širokova, Ivan Feigl • win.winos Open article on Malpedia
Analysis Summary
Based on the very limited context provided (which points to an article titled "NSIS Abuse and sRDI Shellcode: Anatomy of the Winos 4.0 Campaign"), I will structure the summary by synthesizing the information directly suggested by the title and common knowledge associated with these components (Winos, NSIS Abuse, sRDI Shellcode). **Since the actual content of the article is not provided, the technical details, IOCs, and specific mappings will be based on the known characteristics of Winos, NSIS abuse, and sRDI, using boilerplate placeholders where specific article data is missing.**
# Tool/Technique: Winos (4.0 Campaign) / NSIS Abuse / sRDI Shellcode
## Overview
This summary focuses on the components observed in the Winos 4.0 Campaign, which heavily leverages the legitimate NSIS (Nullsoft Scriptable Install System) framework for initial execution, combined with custom shellcode employing the sRDI technique for process injection and evasion. The overall purpose is likely surveillance or information theft, typical of sophisticated malware campaigns.
## Technical Details
- Type: Malware Family (Winos 4.0) | Technique (NSIS Abuse, sRDI)
- Platform: Windows
- Capabilities: Executable packaging, stealthy injection, memory evasion, C2 communication (inferred).
- First Seen: Campaign details point to May 2025 based on the linked article date.
## MITRE ATT&CK Mapping
*(Note: Mappings are inferred based on the techniques mentioned in the title.)*
- **TA0002 - Execution**
- T1204.002 - User Execution: Malicious File
- T1547.001 - Registry Run Keys / Startup Folder (Often used by installers)
- **TA0003 - Persistence**
- T1547.001 - Registry Run Keys / Startup Folder (Inferred via NSIS delivery)
- **TA0005 - Defense Evasion**
- T1055 - Process Injection (Via sRDI)
- **TA0011 - Command and Control**
- T1071 - Application Layer Protocol (Inferred)
## Functionality
### Core Capabilities
- **NSIS Abuse:** Utilizing NSIS installers to deliver and execute malware payloads, often masking malicious scripts as legitimate setup routines.
- **Payload Staging:** Using the NSIS scripting environment to unpack and launch the final stage malware.
### Advanced Features
- **sRDI (Shellcode Reflective DLL Injection):** A technique to load shellcode (likely a DLL proxy or stage) into a remote process without dropping a visible DLL file to disk, significantly improving evasion capabilities against file-scanning AV/EDR.
- **In-Memory Execution:** The shellcode is executed directly from memory after being decoded/deobfuscated.
## Indicators of Compromise
*(Note: Actual IOCs for Winos 4.0 are not available in the context provided. These are placeholders.)*
- File Hashes: [Specific hashes for Winos binaries/NSIS installers in the campaign]
- File Names: [Common names used by Winos installers or generated files]
- Registry Keys: [Potential run keys created by the NSIS installer]
- Network Indicators: [Known C2 domains utilized by the Winos infrastructure - defanged]
- Behavioral Indicators: Unusual memory allocations or API calls associated with custom shellcode loaders (e.g., unusual usage of `VirtualAllocEx`, `NtQueueApcThread`).
## Associated Threat Actors
- Winos (Specific campaign attribution often requires further analysis, typically linked to state-sponsored or high-level cybercrime groups when utilizing advanced techniques like sRDI).
## Detection Methods
- **Signature-based detection:** Signatures for known Winos payload hashes or signatures detecting NSIS bytecode patterns associated with known malicious scripts.
- **Behavioral detection:** Monitoring for processes spawning unusual child processes or executing memory-only code injection techniques (sRDI indicators).
- **YARA rules:** Rules targeting known static strings or embedded PE headers within the shellcode payload.
## Mitigation Strategies
- **Prevention measures:** Restricting execution of unsigned or unusual installers (e.g., NSIS packages) from untrusted sources. Application whitelisting.
- **Hardening recommendations:** Implementing robust EDR solutions capable of monitoring remote thread creation and in-memory code injection attempts (e.g., monitoring calls related to `LdrLoadDll` analogs used in sRDI).
## Related Tools/Techniques
- Traditional DLL injection methods (if sRDI is an evolution).
- Other legitimate software installers abused for malware delivery (e.g., MSI, Inno Setup).