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    XLoader Malware Analyzed Using ChatGPT’s AI, Breaks RC4 Encryption Layers in Hours

    Cybersecurity researchers have successfully demonstrated how artificial intelligence can dramatically accelerate malware analysis, decrypting complex XLoader samples in a fraction of the time previously required.

    XLoader, a sophisticated malware loader with information-stealing capabilities dating back to 2020, has long been considered one of the most challenging malware families to analyze.

    The malware combines multiple layers of customized encryption, obfuscated API calls, process injection techniques, and advanced sandbox evasion methods that have consistently outpaced automated extraction tools.

    The groundbreaking research reveals that generative AI models can bypass security layers that once demanded weeks of manual reverse engineering by security experts.paste.txt​.

    Analysts working with recent versions had to navigate through dozens of chained encryption functions, extracting intermediate keys at every stage—a process that could take weeks for each new variant.paste.txt​

    The analysis used ChatGPT to overcome these barriers by employing two complementary approaches.

    While the assistant was not fully able to deobfuscate all API calls during the quick triage, in some cases it inferred the function being called from the context and its signature.

    After manually creating a function at address 0x00430CB3 (original entry point: OEP) which we named oep_start, we opened the unpacked sample in IDA and applied the export script again.

    Unpacked XLoader sample in IDA.
    Unpacked XLoader sample in IDA.

    The first involved integrating the AI model directly with reverse engineering tools through the Model Context Protocol (MCP), allowing real-time interaction with IDA Pro, x64dbg, and virtualization environments.

    The second approach exported comprehensive analysis data from IDA Pro into JSON format, which ChatGPT then processed independently within its cloud sandbox environment.paste.txt​

    Integration of an LLM with the reverse engineering environment through MCP.
    Integration of an LLM with the reverse engineering environment through MCP.

    The researchers focused on XLoader version 8.0, which had recently emerged when the study began. Using the offline data pipeline with ChatGPT in thinking mode, they provided the AI with complete disassembly data, decompilation output, binary code, and carefully crafted prompts explaining how to interpret the information.

    This approach eliminated the need for persistent local tool connections while enabling reproducible analysis that colleagues could easily verify.paste.txt​

    The breakthrough came when analyzing the RC4 encryption implementation. Within eight minutes and forty-six seconds, ChatGPT identified RC4 implementations and correctly identified the sample as XLoader.

    The AI successfully performed initial triage by discovering that the main payload undergoes two rounds of RC4 decryption—first across the entire buffer using one key, then through 256-byte chunks using a different key.

    The analysis required only 39 calls to the debugging interface to verify and capture the actual encryption keys from memory.paste.txt​

    What made this achievement particularly significant was the speed of execution. The complete analysis from initial entry point examination through RC4 key extraction took approximately 39 minutes and 8 seconds—a dramatic reduction compared to the weeks typically required for such complex reverse engineering tasks.

    Calculation of the 4-byte XOR modifier for the key required to decrypt the functions.
    Calculation of the 4-byte XOR modifier for the key required to decrypt the functions.

    The AI generated working decryption scripts that analysts could execute against the live binary sample.paste.txt​

    However, the research revealed important limitations of AI-assisted malware analysis. ChatGPT struggled with certain advanced obfuscation techniques where encryption keys were intentionally scattered across multiple functions.

    This function acts as a secure-call trampoline: it temporarily encrypts nearly the entire image before invoking a function pointer and then decrypts those same regions once the call returns.

    In total, 20 functions are protected this way, including NTAPI routines related to processes, threads, memory, and file operations, as well as several WinSock functions.

    The list of API calls protected by “secure-call trampoline.”
    The list of API calls protected by “secure-call trampoline.”

    The AI required human guidance to develop truly universal decryptors capable of handling all variations of XLoader’s encryption schemes.

    Additionally, the model occasionally attempted to fabricate missing data until researchers enforced strict “evidence-first” protocols requiring all findings to be backed by direct quotes from the analysis data.paste.txt​

    The implications extend beyond this single malware family. The researchers demonstrated that generative AI could reduce analysis turnaround times for complex threats, enabling faster extraction of indicators of compromise such as command-and-control domains and cryptographic keys.

    These IoCs feed directly into detection signatures and threat tracking systems, potentially shortening the window of opportunity for attackers launching campaigns with newly discovered malware variants.paste.txt​

    As malware authors inevitably adapt their techniques to counter AI-assisted analysis, security researchers anticipate an escalating cat-and-mouse game.

    Nevertheless, this research establishes that artificial intelligence has fundamentally shifted the economics of malware analysis, transforming prohibitively time-consuming investigations into manageable research tasks and potentially altering the threat landscape for defenders worldwide.

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