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Arnold Chan

@slaz
Trusted contributorCompletionist
2 followers2,099 downloads4,370 copies51 likes26,065 views

7,555 detections

This rule detects attempts by users to disable or clear command line history logs for shell environments, including PowerShell (e.g., modifying PSReadLine history) and Unix-like shells (e.g., unset HISTFILE, setting HISTSIZE to 0, or disabling history collection). Such actions are frequently performed by adversaries to hinder incident response and forensic analysis by obscuring their post-exploitation activity.
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Arnold Chan@slaz
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Hunters
2 months ago
001
Detects the creation, modification, or renaming of unsigned executable files (.exe, .dll, .sys, .efi) within critical Windows system directories (System32, SysWOW64, drivers, boot). The rule excludes activity triggered by known trusted OS update processes, such as TrustedInstaller or Windows Update services, and optionally flags occurrences outside defined maintenance windows.
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Arnold Chan@slaz
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Hunters
2 months ago
001
Detects high-frequency file creation, modification, or renaming activity involving files with the specific '.df_win' extension, likely indicative of mass encryption activity or automated ransomware behavior. The rule excludes known backup and security software processes to reduce noise.
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Arnold Chan@slaz
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Hunters
2 months ago
001
Detects unauthorized processes accessing sensitive web browser files (login data, cookies, local state) from suspicious or non-standard paths. This is a common behavioral pattern for infostealers attempting to exfiltrate user credentials and browser session tokens.
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Arnold Chan@slaz
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Hunters
2 months ago
001
Detects anomalous, non-interactive sign-in activity in Microsoft 365 that suggests session cookie replay (Pass-the-Cookie). The rule correlates successful, MFA-validated interactive sign-ins against subsequent, non-interactive sign-ins that lack MFA, occur from a different device and IP address within a short time window, and bypass standard interactive re-authentication.
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Arnold Chan@slaz
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Hunters
2 months ago
001
Detects successful VPN logins following a burst of failed attempts from multiple IP addresses, where the successful login originates from a known malicious IP or an IP associated with the preceding failed attempts. This rule specifically identifies potential credential stuffing or password spraying activity targeting VPN services, often associated with the BlackSuit ransomware group.
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Arnold Chan@slaz
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Hunters
2 months ago
101
Detects the download of ZIP files with filenames matching known phishing patterns associated with NFe (Nota Fiscal Eletrônica) campaigns, correlated with access to specific malicious or suspicious download URLs within a 15-minute window.
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Arnold Chan@slaz
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Hunters
2 months ago
001
Detects the execution of known Windows update-related binaries (UpdateAssistant.exe or AppUpdateHelper.exe) from non-standard, suspicious locations within AppData directories. This behavior is indicative of masquerading, where an adversary attempts to blend in by using a legitimate process name from an unexpected path.
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Arnold Chan@slaz
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Hunters
2 months ago
001
This rule detects sophisticated phishing lure pages impersonating DocuSign or NFe documentation. It specifically identifies pages that implement multi-layered anti-bot gating techniques, including detection of browser automation (navigator.webdriver), identification of headless browser artifacts (headless/HeadlessChrome), and the presence of interaction-wait fallback timers using addEventListener, all tied to specific malicious content indicators.
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Arnold Chan@slaz
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Hunters
2 months ago
001
Detects a specific pattern of PowerShell execution involving the download of files from a remote endpoint using parameters associated with Brazilian tax documents (NotaFiscal) to the Desktop directory, followed by immediate execution. The rule looks for a combination of hidden window style, Invoke-WebRequest, specific URL parameters (dl.php, NFe identifiers), and subsequent Start-Process calls, which is indicative of malware dropper activity.
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Arnold Chan@slaz
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Hunters
2 months ago
001
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