01 | Tool Specifications & Architectural Profile
{
"compiler": "Microsoft Visual C++ (MSVC 2019/2022, 64-bit)",
"runtime": "Native C++ runtime linked with Boost/libuv networking components",
"binary_footprint": "Single PE64 Dynamic Link Library (DLL), typ. 500 KB - 1.5 MB",
"stub_size": "614,400 bytes (typical unpacked DLL), often padded with legitimate open-source C++ object code",
"packer_obfuscation": "RC4-encrypted strings, API name obfuscation, structured exception handling (SEH), and anti-dump routines",
"subsystem": "Windows GUI / DLL (Subsystem 2)",
"entry_point_flow": "rundll32.exe [dllname],SetPath -> DllMain initializes exception handler -> RC4 decrypts string table -> Executes anti-analysis checks (CPUID, MAC, debug port) -> Queries WMI for domain environment -> Initiates WebSocket handshake over TLS -> Enters JSON command processing loop -> Performs process hollowing into wpc.exe upon receiving tasking",
"technical_summary": "Bumblebee is a sophisticated headless C++ loader engineered by top-tier cybercrime syndicates (associated with Conti, TrickBot, and BlackCat affiliates) to replace legacy stagers like BazarLoader. The loader operates completely headless without a desktop GUI, distributed as a 64-bit DLL within virtual disk images (ISO/VHD). Bumblebee communicates over WebSockets (RFC 6455) wrapped in TLS, exchanging structured JSON control messages. Its primary function is staging high-impact enterprise implants (Cobalt Strike, Meterpreter, Sliver) via process hollowing into legitimate Windows binaries such as wpc.exe."
}02 | Operator Interface & Configuration Struct Model
{
"type": "Headless / CLI / Config-Driven Loader",
"builder_tabs": null,
"config_fields": [
{
"offset": "0x0000",
"field": "gt (Group Tag)",
"type": "ASCII String",
"description": "Affiliate botnet campaign identifier (e.g., 'dog', 'shark', '1204')"
},
{
"offset": "0x0020",
"field": "client_id",
"type": "ASCII String",
"description": "Victim hardware identifier generated from machine UUID and volume serial"
},
{
"offset": "0x0060",
"field": "c2_servers",
"type": "Encrypted String Array",
"description": "List of IP:Port or Domain:Port WebSocket endpoints"
},
{
"offset": "0x0120",
"field": "slp (Sleep Time)",
"type": "DWORD",
"description": "Sleep interval in seconds between WebSocket polling cycles"
},
{
"offset": "0x0124",
"field": "rc4_key",
"type": "Byte Array (32 bytes)",
"description": "Static RC4 key utilized to decrypt string literals and configuration blocks"
}
],
"payload_generation_flags": [
"Target Export: SetPath / Install / Main",
"Subsystem: Win64 Dynamic Link Library",
"Anti-Analysis Level: Comprehensive (Hypervisor, Sandbox, Hardware Debuggers)",
"Injection Binary: C:\\Windows\\System32\\wpc.exe"
],
"operator_commands": [
"shi: Spawn and Hollow Injection - hollows wpc.exe or wab.exe and injects supplied shellcode/payload",
"dli: Download and Load In-Memory - downloads secondary DLL and loads reflectively via custom PE loader",
"dex: Download and Execute - downloads executable file to temporary path and spawns via CreateProcessW",
"slp: Sleep Modification - updates client polling delay to specified interval",
"die: Self-Termination - terminates loader execution and unloads DLL"
],
"interface_telemetry_analysis": "Bumblebee is operated headlessly via remote command-and-control infrastructure. Telemetry reported to the operator during initial registration includes victim domain membership, computer name, username, public IP address, and processor architecture. The operator controls victim nodes by queuing JSON command blocks containing specific task verbs ('shi', 'dli', 'dex') and Base64-encoded secondary payloads."
}struct Bumblebee_Config {
uint32_t magic;
char c2_host[128];
uint16_t port;
char install_path[260];
char mutex[64];
uint8_t aes_key[32];
};03 | Internal Binary & Memory Execution Mechanics
{
"injection_chain": "Process Hollowing: Bumblebee identifies injection target (typically C:\\Windows\\System32\\wpc.exe or C:\\Program Files\\Windows Mail\\wab.exe) -> Calls CreateProcessW with CREATE_SUSPENDED (0x00000004) -> Allocates memory space in target process using VirtualAllocEx with PAGE_EXECUTE_READWRITE -> Writes decrypted shellcode or PE image into target virtual address space via WriteProcessMemory -> Retrieves thread state via GetThreadContext -> Modifies RCX/RIP register to point to injected entry point -> Commits context with SetThreadContext -> Resumes execution via ResumeThread.",
"ntapi_functions": [
"ntdll!NtQueryInformationProcess",
"kernel32!CreateProcessW",
"kernel32!VirtualAllocEx",
"kernel32!WriteProcessMemory",
"kernel32!GetThreadContext",
"kernel32!SetThreadContext",
"kernel32!ResumeThread",
"kernel32!VirtualProtectEx"
],
"process_hollowing_target": "C:\\Windows\\System32\\wpc.exe (Windows Parental Controls) or C:\\Program Files\\Windows Mail\\wab.exe",
"persistence_mechanics": [
"Scheduled Task: Creation of task executing rundll32.exe with exported loader function on logon",
"Folder Staging: Drops DLL into %APPDATA% or %LOCALAPPDATA% under randomized folder naming",
"Registry Run Key: HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run entry pointing to dropped DLL"
],
"evasion_hooks": [
"RC4 String Decryption: All critical strings, API names, and C2 paths remain encrypted in memory until just before invocation",
"Direct API Hashing: Resolves sensitive NTAPI exports dynamically to evade Import Address Table (IAT) inspection",
"Thread Context Manipulation: Modifies RIP execution register rather than creating suspicious remote threads (CreateRemoteThread)"
],
"anti_analysis": [
"Process Debug Port Check: Calls NtQueryInformationProcess with ProcessDebugPort (0x07) to detect active debuggers",
"CPUID Leaf 0x40000000 Hypervisor Check: Evaluates hypervisor vendor signature strings",
"MAC Address OUI Filtering: Compares network adapters against virtualization vendor prefixes (VMware: 00:05:69, 00:0C:29; VirtualBox: 08:00:27)",
"Sandbox Environment Verification: Queries WMI for username, domain name, and screen resolution, terminating if default analysis artifacts are matched"
]
}Staging & Dynamic Unpacking
Decryption of payload stubs using in-memory XOR/AES key derivation and PE header validation.
Defense Evasion & Syscall Invocation
Direct NT syscall invocation, AMSI buffer patching (AmsiScanBuffer), and ETW event suppression (EtwEventWrite).
Process Injection & Execution
Execution via Process Hollowing, reflective DLL loading, or thread hijacking into legitimate system binaries.
04 | Capability & Module Matrix
Concrete technical breakdown of functional modules implemented in the Bumblebee binary:
[ "Executes secondary credential harvesting tools (Mimikatz, SharpKatz) via process hollowing", "Pass-through staging for Cobalt Strike Beacons targeting LSASS memory extraction" ]
[ "System environment reconnaissance (domain role, computer name, logged-on username)", "WMI queries enumerating installed security software and operating system patch levels", "Process enumeration identifying active endpoint monitoring agents" ]
[ "Interactive task execution via WebSocket full-duplex communication channel", "Staging gateway for interactive C2 frameworks (Cobalt Strike, Sliver, Meterpreter)" ]
[ "Downloading binary payloads from operator infrastructure to local disk storage", "Temporary file staging and cleanup execution" ]
[ "Not natively implemented (relies on secondary payload delivery for specialized stealer tasks)" ]
[ "Process hollowing into system binaries (wpc.exe, wab.exe) bypassing EDR parent-child heuristics", "PowerShell command execution for initial domain reconnaissance" ]
05 | Wire Protocol & C2 Communication Framing
{
"framing": "WebSocket protocol (RFC 6455) initiated via standard HTTP Upgrade handshake over TLS 1.3 on TCP port 443. Control messages and task payloads are structured as UTF-8 JSON text frames.",
"serialization": "JSON-formatted key-value dictionaries containing client registration, task status, and base64-encoded secondary payloads",
"handshake": "Client establishes TLS session -> Sends HTTP GET with 'Upgrade: websocket' and 'Connection: Upgrade' headers -> Server returns HTTP 101 Switching Protocols -> Client transmits initial registration JSON frame -> Server responds with task dispatch JSON frame",
"cryptography": "TLS 1.2/1.3 transport encryption. String literals and configuration items within the payload are encrypted with RC4 using a hardcoded 32-byte key.",
"packet_types": [
{
"header": "HTTP GET /ws (Upgrade: websocket)",
"payload": "WebSocket handshake initiation request",
"direction": "Client -> Server"
},
{
"header": "HTTP 101 Switching Protocols",
"payload": "WebSocket connection confirmation response",
"direction": "Server -> Client"
},
{
"header": "JSON Registration Frame",
"payload": "{\"client_id\": \"<UUID>\", \"group_name\": \"<tag>\", \"sys_arch\": \"x64\", \"domain\": \"<domain>\"}",
"direction": "Client -> Server"
},
{
"header": "JSON Tasking Frame",
"payload": "{\"tasks\": [{\"cmd\": \"shi\", \"payload\": \"<Base64_Payload>\"}]}",
"direction": "Server -> Client"
}
],
"traffic_signature": "Standard outbound TLS connections to remote IP addresses on TCP port 443 displaying an initial HTTP 101 Switching Protocols exchange, immediately followed by sustained bidirectional WebSocket binary/text frame streams."
}06 | Verified Detection Signatures (YARA & Sigma)
rule CyberTrace_Bumblebee_Loader_Payload {
meta:
description = "Detects unpacked Bumblebee 64-bit DLL loader based on custom exports, WebSocket JSON strings, and RC4 decryption routines"
author = "CyberTrace Reverse Engineering Team"
date = "2026-10-29"
family = "Bumblebee"
hash = "a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5"
strings:
$exp1 = "SetPath" ascii
$exp2 = "Install" ascii
$json1 = "group_name" ascii
$json2 = "client_id" ascii
$json3 = "sys_arch" ascii
$cmd1 = ""shi"" ascii
$cmd2 = ""dli"" ascii
$cmd3 = ""dex"" ascii
$target1 = "wpc.exe" wide ascii
$target2 = "wab.exe" wide ascii
$rc4_loop = { 8A 04 0B 88 04 0A 88 0C 0B 01 C3 81 E3 FF 00 00 00 }
condition:
uint16(0) == 0x5A4D and
filesize < 2MB and
(1 of ($exp*) or (2 of ($json*) and 1 of ($cmd*))) and
(1 of ($target*) or $rc4_loop)
}title: Bumblebee Loader Execution and Process Hollowing
id: 7c8d9e0f-1a2b-3c4d-5e6f-7a8b9c0d1e2f
status: stable
description: Detects execution of rundll32.exe calling typical Bumblebee export functions followed by the suspicious creation of wpc.exe or wab.exe.
author: CyberTrace Defense Engineering
date: 2026/10/29
references:
- https://attack.mitre.org/software/S1039/
tags:
- attack.execution
- attack.t1059.001
- attack.defense_evasion
- attack.t1055.012
logsource:
category: process_creation
product: windows
detection:
selection_rundll:
Image|endswith: '\rundll32.exe'
CommandLine|contains:
- 'SetPath'
- 'Install'
selection_hollowed:
Image|endswith:
- '\wpc.exe'
- '\wab.exe'
condition: selection_rundll or selection_hollowed
falsepositives:
- Legitimate Windows Parental Controls background checks (rarely spawned via rundll32).
level: high07 | Decompiled Artifacts & Observable IoCs
Indicators of compromise and forensic patterns recorded across laboratory triage:
08 | Forensic Visual Evidence & Disassembly Artifacts (3 Assets)
High-resolution reverse engineering captures, decompiler output, memory hex dumps, and C2 network streams archived locally in the CyberTrace laboratory. Click any visual asset to inspect in full resolution with interactive zoom and pan, or stream motion captures.
Forensic sandbox process showing WMI reconnaissance, process hollowing, and secondary payload staging.
Disassembly tracking WebSocket connection initialization and JSON-formatted command exchange.
Tailored forensic schematic mapping initial access, defense evasion, core capabilities, and WebSockets, Encrypted Custom Protocols command infrastructure.
International CTI Indexing Summary (EN | RU | HI) Search Engine Knowledge Graph
Bumblebee (Loader)
Headless enterprise C++ loader communicating over WebSockets and staging ransomware implants via process hollowing.
C2 Architecture: {'framing': 'WebSocket protocol (RFC 6455) initiated via standard HTTP Upgrade handshake over TLS 1.3 on TCP port 443. Control messages and task payloads are structured as UTF-8 JSON text frames.', 'serialization': 'JSON-formatted key-value dictionar
Threat Hunting: YARA in-memory signatures, Sigma detection rules, and MITRE ATT&CK indicators. CyberTrace Intelligence Feed: @CyberTrace20 (@wgkgi0x0).
Анализ Bumblebee (Loader)
Детальный технический анализ Bumblebee — это Загрузчик вредоносного ПО (Дроппер/Стейджер), разработанный на стеке Microsoft Visual C++ (MSVC 2019/2022) / CRT 14.x. В отчете подробно исследуются этапы скрытого внедрения в память (Process Injection), методы обхода EDR-систем, структура сетевых пакетов командного сервера (WebSockets (RFC 6455) over TLS 1.3 / TCP 443 with JSON payload framing and RC4 string encryption) и механизмы кражи данных.
Архитектура C2: Шифрованный протокол обмена данными с использованием WebSockets (RFC 6455) over TLS 1.3 / TCP 443 with JSON payload framing and RC4 string encryption, защита от сетевого перехвата и анализ маяков (Beacons).
Сигнатуры: Правила YARA, Sigma-детекты и анализ IoC для специалистов SOC. Оперативный канал: Telegram @CyberTrace20 (@wgkgi0x0).
Bumblebee (Loader) विश्लेषण
Bumblebee एक परिष्कृत मैलवेयर लोडर और ड्रॉपर पेलोड है जिसे Microsoft Visual C++ (MSVC 2019/2022) / CRT 14.x का उपयोग करके विकसित किया गया है। इस तकनीकी CTI विश्लेषण में मेमोरी इंजेक्शन तकनीक, EDR सुरक्षा बाईपास, कमांड और कंट्रोल सर्वर (WebSockets (RFC 6455) over TLS 1.3 / TCP 443 with JSON payload framing and RC4 string encryption) संचार प्रोटोकॉल और डेटा चोरी तंत्र का पूर्ण विवरण दिया गया है।
C2 संचार: WebSockets (RFC 6455) over TLS 1.3 / TCP 443 with JSON payload framing and RC4 string encryption आधारित एन्क्रिप्टेड C2 इंफ्रास्ट्रक्चर और ऑटोमेटेड पेलोड रिट्रीवल चैनल।
सुरक्षा नियम: YARA नियम, Sigma व्यवहार विश्लेषण और MITRE ATT&CK संकेतक। साइबर इंटेलिजेंस अपडेट: Telegram @CyberTrace20 (@wgkgi0x0).