Sigma detection rules, expert-reviewed

ValleyRat Beacon Sideloading via NtHandleCallback Loading log.dll (via image_load)

This rule detects the NtHandleCallback.exe process loading log.dll from its working directory, the DLL sideloading pair used to launch the ValleyRat beacon in the Silver Fox campaign. Adversaries leverage a masqueraded executable and a co-located malicious DLL to run the beacon under a benign-looking process, making detection valuable for surfacing command-and-control staging.

Malicious Microsoft Defender Service Components Status Disabled - Registry via Sysmon (via process_creation)

This rule detects disable Defender security features by modifying service configuration in registry.

Masquerading Scheduled Task Masquerading as WindowsUpdate with One-Minute Interval (via process_creation)

This rule detects creation of a scheduled task named WindowsUpdate configured to run every minute, a persistence behavior used by the Anivia loader for rapid respawn of OctoRAT. Adversaries leverage a benign-sounding task name and an aggressive minute interval to keep the implant resident on the host.

Suspicious Parallax RAT Startup Folder Executable Persistence via File System (via file_event)

This rule detects creation of an executable named milk.exe in the Windows Startup folder, the persistence artifact used by the Parallax RAT. It is associated with a campaign targeting cryptocurrency entities with Parallax RAT as reported by Uptycs. Dropping an executable directly into Startup guarantees relaunch at logon, so this artifact indicates established persistence by the RAT.

Suspicious Scheduled Task Launching VBScript From ProgramData (via process_creation)

This rule detects schtasks creating a minute-interval task that runs a VBScript from ProgramData. The AgentTesla loader registers such a task to repeatedly re-launch its VBS staging script.

Malicious PsExec Service Installation via PSEXESVC

This rule detects installation of the PSEXESVC service on a target host which is created when Sysinternals PsExec is used for remote command execution as described in the WithSecure lateral movement lab. Attackers routinely abuse PsExec for hands on keyboard lateral movement so a PSEXESVC service install on a system that does not routinely receive one is a strong lateral movement indicator.

Suspicious VBScript Dropped to Startup Folder (via file_event)

This rule detects Hive0051 GammaInstall and GammaSteel persistence where a randomly named VBScript launcher is written to the user Startup folder so it executes at every logon. Writing a vbscript file directly under the Start Menu Programs Startup path is uncommon for legitimate software. The behavior provides logon persistence for the loader chain.

Suspicious Registry Modification Disabling RestrictedAdmin Mode (via process_creation)

This rule detects a reg add command disabling RestrictedAdmin mode under the LSA key. The SLOW#TEMPEST campaign disabled this protection to enable pass-the-hash remote desktop logons during lateral movement.

Suspicious Credential Store Access for WinSCP and PuTTY via PowerShell (via ps_script)

This rule detects PowerShell script content referencing WinSCP and PuTTY session registry stores or the Windows Credential Manager enumeration API, the credential theft behavior of the SEO poisoning infostealer. These paths and calls harvest saved SSH, SFTP and enterprise credentials. Scripts touching these secrets stores are a strong credential access indicator.

AnyDesk Network

Detects use of AnyDesk

Suspicious Child Process Spawned From Java Following Web Exploitation

This rule detects a Java process spawning a command shell or discovery utility, the post-exploitation behavior seen after ShinyHunters exploited the Oracle PeopleSoft PeopleTools zero-day to gain code execution. A Java application server launching cmd, PowerShell or reconnaissance commands is a strong web-exploitation indicator. This pattern precedes remote-management deployment and lateral movement.

Suspicious Child Process Spawned by 3CXDesktopApp via Supply Chain Compromise

This rule detects the 3CXDesktopApp.exe process spawning a command interpreter such as cmd.exe or powershell.exe. During the 3CX supply chain compromise the trojanized client executed follow-on commands to profile the host and retrieve second-stage payloads after sideloading a malicious ffmpeg.dll. The VoIP client has no legitimate reason to launch shells.

Suspicious Efimer Persistence via Run Controller Value (via registry_set)

This rule detects creation of a controller value under the current user Run key used by the Efimer crypto-stealing Trojan for persistence. Efimer spreads through mass-mailing and installs a clipboard hijacker that swaps cryptocurrency wallet addresses. The named autorun entry re-launches the controller component at every logon.

Suspicious Process Execution From Recycle Bin Directory

This rule detects execution of an executable located inside a Recycle Bin directory such as RECYCLER.BIN or $Recycle.Bin. In a case analyzed by Kaspersky a CEFHelper.exe payload was launched from RECYCLER.BIN on a USB drive to enable DLL sideloading. Legitimate software is not executed from the Recycle Bin so this location strongly indicates staging of a hidden payload for defense evasion.

Malicious Veeam Credential Extraction via sqlcmd Query (via process_creation)

This rule detects the use of sqlcmd to query the Credentials table of the VeeamBackup database, a technique used in Akira ransomware intrusions to recover stored backup infrastructure credentials for lateral movement and backup destruction. Direct sqlcmd access to the Veeam credential table is not typical of routine administration.