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KittyLoader
Caution
Disclaimer & Legal Notice
This repository, KittyLoader, and all associated code, techniques, and information are provided strictly for educational and academic research purposes.This sample and its methodologies have been proactively disclosed to relevant cybersecurity defense organizations and vendors. It is actively used by defensive engineers to research attack patterns, develop detection capabilities, and enhance security products.
You are required to use this knowledge and these tools only on systems you own or have explicit, written permission to test.
Any unauthorized use against systems you do not own is illegal and strictly prohibited.This tool was created to advance the field of defensive cybersecurity. The author, tlsbollei, assumes no liability and is not responsible for any misuse or damage caused by this software.
By accessing this repository, you acknowledge that you understand its purpose is to learn about modern malware techniques, evasion tactics, and ultimately to improve our collective ability to defend against them.
By proceeding, you agree to use this information responsibly and legally.
About
KittyLoader is a highly evasive loader written in C / Assembly.
Features
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Hijacks early execution by replacing the C runtime entrypoint (__scrt_common_main_seh) with custom assembly.
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Hides all modules by walking PEB->Ldr lists and unlinking its module entry (LDR_DATA_TABLE_ENTRY) from :
- InLoadOrderModuleList
- InInitializationOrderModuleList
- InMemoryOrderModuleList
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Deploys a wide variety of anti-analysis techniques, including :
- multilayer scoring (debugger, sandbox/resources, API integrity/hook checks, human-input entropy, contextual cues like domain/time of day) combined into a weighted overall confidence that continuously re-evaluates
- picks an operational state (full → halted) and throttles/pauses with jittered, CPU-cycle-based delays in a loop that keeps reassessing the environment.
- API integrity/inline-hook heuristics and light tamper probes; human-interaction entropy sampling; randomized yet precise timing jitter to throw off debuggers
- adds controlled noise (junk calcs + jittered delays) and spreads logic across multiple signals, reducing single-indicator detection.
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API Resolution via Export Hashing :
- Avoids static imports by resolving function addresses at runtime.
- Walks IMAGE_EXPORT_DIRECTORY and applies custom xor rotate hash algo.
- APIs are initially attempted to be resolved via tprtdll.dll, which is quite the modern technique, it does so using GetModuleHandleW(L"tprtdll.dll") with DONT_RESOLVE_DLL_REFERENCES to minimize operation footprint.
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Embedded payload is encrypted at rest, with key and nonce derived at runtime from entropy sources: PID, TID, QPC, memory load, CPU info (CPUID), tick count.
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Preferred algo is ChaCha20, but in case of failure falls back to RC4, decryption occurs in place after the encrypted blob is copied into memory.
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Searches process memory via VirtualQuery for an already-executable region large enough for the shellcode.
- If none found, allocates new RW region with NtAllocateVirtualMemoryEx
- After decryption, if memory was RW, flips to RX with NtProtectVirtualMemory.
- Therefore, we intend to initially inject into pre-existing RWX memory page, but in case of failure, resort to custom resolved NtAllocateVirtualMemoryEx and flip RW-RX
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Execute via LdrCallEnclave, normally intended for SGX/VBS enclaves, instead of jumping to a secure enclave, we jump to an arbitrary function pointer in normal (VTL0) user memory.
