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## smss.exe **Session Manager**.\ Session 0 starts **csrss.exe** and **wininit.exe** (**OS** **services**) while Session 1 starts **csrss.exe** and **winlogon.exe** (**User** **session**). However, you should see **only one process** of that **binary** without children in the processes tree. Also, sessions apart from 0 and 1 may mean that RDP sessions are occurring. ## csrss.exe **Client/Server Run Subsystem Process**.\ It manages **processes** and **threads**, makes the **Windows** **API** available for other processes and also **maps drive letters**, create **temp files**, and handles the **shutdown** **process**. There is one **running in Session 0 and another one in Session 1** (so **2 processes** in the processes tree). Another one is created **per new Session**. ## winlogon.exe **Windows Logon Process**.\ It's responsible for user **logon**/**logoffs**. It launches **logonui.exe** to ask for username and password and then calls **lsass.exe** to verify them. Then it launches **userinit.exe** which is specified in **`HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon`** with key **Userinit**. Mover over, the previous registry should have **explorer.exe** in the **Shell key** or it might be abused as a **malware persistence method**. ## wininit.exe **Windows Initialization Process**. \ It launches **services.exe**, **lsass.exe**, and **lsm.exe** in Session 0. There should only be 1 process. ## userinit.exe **Userinit Logon Application**.\ Loads the **ntduser.dat in HKCU** and initialises the **user** **environment** and runs **logon** **scripts** and **GPO**. It launches **explorer.exe**. ## lsm.exe **Local Session Manager**.\ It works with smss.exe to manipulate user sessions: Logon/logoff, shell start, lock/unlock desktop, etc. After W7 lsm.exe was transformed into a service (lsm.dll). There should only be 1 process in W7 and from them a service running the DLL. ## services.exe **Service Control Manager**.\ It **loads** **services** configured as **auto-start** and **drivers**. It's the parent process of **svchost.exe**, **dllhost.exe**, **taskhost.exe**, **spoolsv.exe** and many more. Services are defined in `HKLM\SYSTEM\CurrentControlSet\Services` and this process maintains a DB in memory of service info that can be queried by sc.exe. Note how **some** **services** are going to be running in a **process of their own** and others are going to be **sharing a svchost.exe process**. There should only be 1 process. ## lsass.exe **Local Security Authority Subsystem**.\ It's responsible for the user **authentication** and create the **security** **tokens**. It uses authentication packages located in `HKLM\System\CurrentControlSet\Control\Lsa`. It writes to the **Security** **event** **log** and there should only be 1 process. Keep in mind that this process is highly attacked to dump passwords. ## svchost.exe **Generic Service Host Process**.\ It hosts multiple DLL services in one shared process. Usually, you will find that **svchost.exe** is launched with the `-k` flag. This will launch a query to the registry **HKEY\_LOCAL\_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost** where there will be a key with the argument mentioned in -k that will contain the services to launch in the same process. For example: `-k UnistackSvcGroup` will launch: `PimIndexMaintenanceSvc MessagingService WpnUserService CDPUserSvc UnistoreSvc UserDataSvc OneSyncSvc` If the **flag `-s`** is also used with an argument, then svchost is asked to **only launch the specified service** in this argument. There will be several processes of `svchost.exe`. If any of them is **not using the `-k` flag**, then that's very suspicious. If you find that **services.exe is not the parent**, that's also very suspicious. ## taskhost.exe This process act as a host for processes running from DLLs. It also loads the services that are running from DLLs. In W8 this is called taskhostex.exe and in W10 taskhostw.exe. ## explorer.exe This is the process responsible for the **user's desktop** and launching files via file extensions. **Only 1** process should be spawned **per logged on user.** This is run from **userinit.exe** which should be terminated, so **no parent** should appear for this process. # Catching Malicious Processes * Is it running from the expected path? (No Windows binaries run from temp location) * Is it communicating with weird IPs? * Check digital signatures (Microsoft artifacts should be signed) * Is it spelled correctly? * Is running under the expected SID? * Is the parent process the expected one (if any)? * Are the children processes the expecting ones? (no cmd.exe, wscript.exe, powershell.exe..?)
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