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Arnold Chan

@slaz
Trusted contributorCompletionist
2 followers2,100 downloads4,386 copies51 likes26,181 views

7,555 detections

This rule identifies a discrepancy between actual network connections processed by HAProxy and the corresponding entries in its server-side logs. Such inconsistencies can indicate the presence of a malicious backdoor compiled into or injected into the HAProxy process, designed to facilitate C2 traffic while evading standard monitoring by suppressing or omitting logging for those connections.
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Arnold Chan@slaz
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Hunters
2 months ago
003
Detects unauthorized attempts to dump the process memory of the Local Security Authority Subsystem Service (LSASS), a common technique used by attackers to harvest credentials from memory. This includes the use of legitimate diagnostic tools like procdump and comsvcs.dll, as well as the identification of resulting dump files in directory paths associated with LSASS.
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Arnold Chan@slaz
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Hunters
2 months ago
103
Detects the RejectDirectSend bypass (null SMTP envelope sender + internal-domain spoof). Tightened to require Microsoft's composite auth verdict OR all of SPF/DKIM/DMARC failing (vs. any one), excludes known-approved Direct Send relay IPs, and excludes likely-legitimate bulk/newsletter traffic via BulkComplaintLevel.
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Arnold Chan@slaz
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Hunters
2 months ago
103
Detects Direct Send bypass (null envelope + internal-domain spoof) using a file/document-sharing lure aimed at leadership. Tightened: added inbound-direction and auth-failure requirements (was previously missing any authentication check, so legitimate SharePoint/OneDrive-style sharing notifications from real internal senders could have matched), delivered-only filter, and case-insensitive recipient/job-title join.
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Arnold Chan@slaz
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Hunters
2 months ago
003
Detects SCL-9 (high-confidence phishing/spam) messages that still reach an inbox, indicating an allow-list or transport-rule override, and enriches with any recent tenant mail-flow admin changes. Rewritten: removed a no-op self-join on EmailEvents and a broken exact-match join against CloudAppEvents' raw audit blob (was comparing a sender address against a whole JSON record and would never match); now excludes messages later auto-remediated (e.g. ZAP-quarantined) via the native LatestDeliveryLocation field, and correlates admin rule/allow-list changes via substring match over a cross join.
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Arnold Chan@slaz
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Hunters
2 months ago
103
Detects Direct Send spearphishing impersonating internal roles (IT/Finance/Procurement) with business-themed lures targeting leadership/finance titles. Rewritten: removed a non-functional sender/recipient substring check and a broken EmailPostDeliveryEvents join that made the rule rarely fire; anchored detection to the actual Direct Send signature (null envelope + domain match) and a direct IdentityInfo join; standardized auth-failure parsing to match the other rules in this set.
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Arnold Chan@slaz
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Hunters
2 months ago
003
Detects suspicious execution of PowerShell or Mshta spawned from Explorer.exe. It looks for specific malicious indicators including references to known malicious domains, PowerShell encoding flags, hidden window arguments, or Mshta HTTP requests, which are common patterns for fileless malware or dropper execution.
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Arnold Chan@slaz
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Hunters
2 months ago
003
Detects the execution of PowerShell with suspicious command-line arguments (e.g., encoded commands, hidden windows) initiated by mshta.exe, excluding instances where a .ps1 script file is involved. This pattern often indicates attempts to bypass execution policy or run obfuscated payloads in memory, which is a common behavior of malicious HTA files.
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Arnold Chan@slaz
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Hunters
2 months ago
103
Detects modifications or creation of InprocServer32 COM registry keys by suspicious processes like mshta.exe or powershell.exe, which is indicative of COM Hijacking for persistence or privilege escalation.
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Arnold Chan@slaz
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Hunters
2 months ago
003
Detects modifications to the Windows Registry that disable Microsoft Defender Tamper Protection. Tamper Protection is a security feature that prevents malicious changes to security settings, including the disabling of antivirus and real-time monitoring.
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Arnold Chan@slaz
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Hunters
2 months ago
203
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