Identifier / Programs / Windows
syssetup.dll
Windows NT System Setup file version info (xCyclopedia)
LOLBAS AWL Bypass, Execute 1 ATT&CK technique 2 documented commands 2 known copies with hashes
How syssetup.dll is abused
AWL Bypass T1218.011 System Binary Proxy Execution: Rundll32
Run by rundll32.exe: syssetup.dll,setupinfobjectinstallaction defaultinstall
Execute T1218.011 System Binary Proxy Execution: Rundll32
Run by rundll32.exe: syssetup.dll,setupinfobjectinstallaction defaultinstall
Each abuse is LOLBAS's category and the options and words it uses; the full write-up is on LOLBAS's page for syssetup.dll.
2 documented commands
AWL Bypass T1218.011 System Binary Proxy Execution: Rundll32 User privileges
Execute the specified (local or remote) .wsh/.sct script with scrobj.dll in the .inf file by calling an information file directive (section name specified).
rundll32 syssetup.dll,SetupInfObjectInstallAction DefaultInstall 128 {PATH_ABSOLUTE:.inf}Trips 1 Sigma rule: mediumPotentially Suspicious Rundll32 Activity by juju4, Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)
Execute T1218.011 System Binary Proxy Execution: Rundll32 User privileges
Launch an executable file via the SetupInfObjectInstallAction function and .inf file section directive.
rundll32 syssetup.dll,SetupInfObjectInstallAction DefaultInstall 128 {PATH_ABSOLUTE:.inf}Trips 1 Sigma rule: mediumPotentially Suspicious Rundll32 Activity by juju4, Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)
All 2 commands the identifier reads trip a Sigma process-creation rule. These commands and their descriptions are from LOLBAS’s entry for syssetup.dll, by LOLBAS Team, 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 syssetup.dll. The identifier reads each 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
Is it the real syssetup.dll?
C:\Windows\system32\C:\Windows\SysWOW64\2 known copies
10.0.19041.1 (WinBuild.160101.0800) · C:\Windows\SysWOW64\syssetup.dll · signed by Microsoft Windows
33dd3b9c831b95b3904218efae3810fcc1583e7bdb8ba4c4fc8e1b7a8abf1b4610.0.19041.1 (WinBuild.160101.0800) · C:\Windows\system32\syssetup.dll · signed by Microsoft Windows
9268f6a26d8f2a82344680a95c241be06ca53f27bc266a4c8d1274d4a7e128feFrom 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.