Elastic Defend high stable eql
Unusual File Written or Modified in Startup Folder
Identifies suspicious file extensions or names written to the startup folder. Adversaries may use this technique to maintain persistence.
Detection Logic
file where event.action != "deletion" and
process.pid != 4 and process.executable != null and
file.name != null and not user.id : ("S-1-5-18", "S-1-5-19", "S-1-5-20") and
file.path : ("?:\\Users\\*\\AppData\\Roaming\\Microsoft\\Windows\\Start Menu\\Programs\\Startup\\*",
"?:\\ProgramData\\Microsoft\\Windows\\Start Menu\\Programs\\StartUp\\*") and
(
/* file extensions rarely written to Startup folder by legit installers */
file.extension : ("exe", "com", "scr", "dll", "hta", "ps1", "cmd", "url", "wsh", "wsf", "vbe", "jse", "sick", "png", "jpg", "manifest", "ahk", "jar") or
/* suspicious file names */
length(file.name) <= 6 or
file.name :
("*Microsoft*",
"*fuck*",
"*:*",
"*.*.",
"*update*",
"*windows*",
"*setup*",
"*googl*",
"*adobe*",
"*chrome*")
) and
not process.executable :
("?:\\Windows\\SysWOW64\\msiexec.exe",
"?:\\Windows\\system32\\msiexec.exe",
"?:\\Windows\\explorer.exe",
"?:\\Windows\\System32\\svchost.exe",
"?:\\Windows\\System32\\dllhost.exe",
"?:\\Windows\\System32\\xcopy.exe",
"?:\\ProgramData\\Microsoft\\Windows Defender\\Platform\\*.exe",
"?:\\ProgramData\\Microsoft\\Windows Defender Advanced Threat Protection\\Platform\\*.exe",
"?:\\Program Files\\Windows Defender Advanced Threat Protection\\*.exe",
"\\Device\\Mup\\*\\SysVol\\*") and
not (process.executable : ("?:\\Program Files\\*.exe", "?:\\Program Files (x86)\\*.exe") and not process.name : "javaw.exe") and
not (process.name : "cmd.exe" and file.extension : "cmd") and
not (process.code_signature.subject_name :
("Intercontinental Exchange, Inc.", "Chocolatey Software, Inc.", "ONELAUNCH TECHNOLOGIES INC.",
"Notepad++", "Ghisler Software GmbH", "Western Union Holdings Inc.", "AnyDesk Software GmbH", "Learnpulse SAS") and
process.code_signature.status : ("trusted", "errorExpired", "errorCode_endpoint*")) and
not (process.executable : "?:\\Windows\\System32\\notepad.exe" and file.extension : ("bat", "cmd")) and
not (process.executable : "C:\\Windows\\SysWOW64\\cscript.exe" and file.name : "WUPOSStartup.exe") and
not (process.name : "cmd.exe" and file.name : "MonitorES.exe") Field Validations
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