customshellhost.exe

CustomShellHost file version info (xCyclopedia)

LOLBAS Execute 1 ATT&CK technique 1 documented command 2 known copies with hashes

How customshellhost.exe is abused

documented by LOLBAS

Execute T1218 System Binary Proxy Execution

Each abuse is LOLBAS's category and the options and words it uses; the full write-up is on LOLBAS's page for customshellhost.exe.

1 documented command

from LOLBAS, each read by the identifier

Execute T1218 System Binary Proxy Execution User privileges

Executes explorer.exe (with command-line argument /NoShellRegistrationCheck) if present in the current working folder.

CustomShellHost.exe

Identify

The command the identifier reads trips no Sigma process-creation rule. These commands and their descriptions are from LOLBAS’s entry for customshellhost.exe, by Wietze Beukema, at commit 2056cb766250 of 2026-09-26, under the GPL-3.0 and LOLBAS’s notice, with no warranty. Changed: Markdown is shown formatted. The source is in lolbas-gtfobins-commands.json.gz, and the full entry is on LOLBAS’s page for customshellhost.exe. The identifier reads it with LOLBAS’s placeholders filled in: a URL as https://example.com/file, a share as \\192.0.2.10\share\file, a path as C:\Data\file and a command as calc.exe.

What detects it

Sigma process creation rules

T1218System Binary Proxy Execution

Is it the real customshellhost.exe?

file version info and known copies

Installed inC:\Windows\system32\

Signed byMicrosoft Windows

ProductMicrosoft Windows Operating System, Microsoft Corporation

DescriptionCustomShellHost

2 known copies

10.0.22000.120 (WinBuild.160101.0800) · C:\WINDOWS\system32\CustomShellHost.exe · signed by Microsoft Windows

a05b28dfead053dce2bcd0ca8cec54650366ae06080561c4170e65dc6886c2db

10.0.19041.1202 (WinBuild.160101.0800) · C:\Windows\system32\CustomShellHost.exe · signed by Microsoft Windows

91333f3282a2420359ae9d3adf537688741d21e964f021e2b152ab293447f289

From the file’s version info and the copies recorded by xCyclopedia (MIT). A copy in another folder, signed by someone else or with another hash is not necessarily malicious, but it is worth a closer look. In Ceplin, "<sha256>".whatis() says which known copy a hash is.