Sigma detection rules, expert-reviewed

WordPress wp2shell Plugin Webshell Access via wp-content/plugins URL Path

Alert on HTTP requests targeting the wp2shell WordPress plugin path used for webshell execution/persistence.

WordPress REST Batch Endpoint (wp2shell) POST Exploitation Activity

Alert on POST requests containing rest_route=/batch/v1 that return HTTP 207, consistent with wp2shell-style REST batch probing/exploitation.

Suspicious Privileged Group Membership Change via net.exe (via process_creation)

This rule detects net.exe adding an account to a privileged local group such as Administrators or Remote Desktop Users. Medusa operators manipulate group membership to escalate privileges and retain access, so an account addition to a sensitive group during an intrusion is a persistence and privilege-escalation signal.

Malicious GitHub Repository Creation With s1ngularity Exfiltration Name

This rule detects a GitHub audit repo create event where the repository name contains s1ngularity, the naming convention of the exfiltration repositories used to publish stolen secrets. It matters because these attacker created repositories are the exfiltration destination in the nx supply chain attack.

Enable WDigest using PowerShell

Rule to detect registry modifications to enable WDigest using powershell over the commandline.

Suspicious SSH Reverse Tunnel Over Port 443 via ssh.exe by UNC1549

This rule detects the native Windows ssh.exe client establishing a reverse tunnel with the -R flag over port 443 as observed in UNC1549 operations. Attackers tunnel internal services outbound over an HTTPS port to blend with normal web traffic and bypass egress controls.

Malicious PowerShell Download Cradle via Invoke-WebRequest and IEX

This rule detects PowerShell run with an execution policy bypass that downloads content and pipes it directly to Invoke-Expression. Stealerium uses powershell -eP Bypass with Invoke-WebRequest to pull an atom feed from a blogspot dead drop and execute it in memory with IEX. This download-and-execute cradle is a widely abused fileless staging technique.

Suspicious Scheduled Task Masquerading as Edge Update Telemetry (via process_creation)

This rule detects creation of a scheduled task using the distinctive name CoreEdgeUpdateServicesTelemetry FallBack. The FLUX#CONSOLE campaign registered this task to run its sideloading Dism binary every five minutes for persistence.

Suspicious Linux Crontab Reboot Persistence to Hidden Sys Cache Binary (via process_creation)

This rule detects the installation of a crontab reboot entry pointing to a hidden .Sys_cache binary under var tmp as used by the Linux SSH CoinMiner campaign. Piping a modified crontab that adds a reboot job to a hidden file is a common miner persistence technique.

Suspicious Execution From WinRAR Temporary Extraction Path via Command Line (via process_creation)

This rule detects process execution referencing the WinRAR temporary extraction directory pattern Rar$ under the local Temp folder, which the CVE-2023-38831 exploit uses to run its planted payload. It is associated with attacks abusing the WinRAR archive spoofing zero-day reported by Uptycs. Because scripts and binaries executed straight from this transient extraction path are characteristic of the exploit, this pattern indicates likely code execution from a crafted archive.

Malicious PlugX Sideload via Acrobat.dll

This rule detects the signed Acrobat.exe loading an Acrobat.dll from a location outside Program Files. This behavior matches CL-STA-0048 where operators sideloaded a malicious Acrobat.dll implementing PlugX which then injected into svchost.exe. A trusted Adobe binary loading its companion DLL from a non-standard path is a sideloading indicator of espionage malware.

Suspicious Silent MSI Installation from AppData Spawned by PowerShell (via process_creation)

This rule detects msiexec.exe spawned by PowerShell to silently install an MSI staged in the user AppData directory, the second step of the Bumblebee loader chain where PowerShell writes y.msi to AppData and installs it with no user interaction. Legitimate software rarely installs MSIs from AppData under a PowerShell parent, so this parent-child and path combination surfaces the loader stage.

Suspicious node.exe Inline Script Execution via -e

This rule detects node.exe executing an inline script through the -e flag, the stager execution method in the DEV#POPPER GitHub-lure infection. Victims who cloned the weaponized repository ran a hidden script that used node -e to bootstrap the RAT. While developers occasionally use node -e, inline Node execution from a cloned project should be reviewed for malicious staging.

Suspicious AppLaunch.exe Execution as Process Hollowing Target

This rule detects the .NET ClickOnce host AppLaunch.exe running with a parent other than a legitimate development tool. Titan Stealer hollows AppLaunch.exe and injects its XOR-decoded Golang stealer into the trusted signed binary to evade detection. AppLaunch.exe spawned outside of Visual Studio or build tooling is a common injection and masquerading target.

Driverquery Lookup

Detects use of driverquery to look up the installed and configured drivers as part of host discovery