csrss.exe
Sources: 300M+ executions observed in the wild.
Summary
Windows Client/Server Runtime Subsystem - manages console windows, thread creation/deletion, and Win32 subsystem. Critical protected process.
csrss.exe is the 283rd most commonly executed Windows program in EchoTrail's dataset, observed 40,481 times across enterprise environments. It typically runs from C:\Windows\System32 and it is most often launched by smss.exe.
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https://api.echotrail.io/v1/process/csrss.exeFree returns the summary. Team returns the full record you see on this page. Endpoint docs
Behavior
Top Paths
- C:\Windows\System3299.99%
- C:\...0.01%
- C:\Windows\Temp\...<0.01%
Top Hashes (SHA256)
- a37d616f86ae31c189a05b695571732073b9df97bf5a5c7a8ba73977ead3e65b23.25%
- cb1c6018fc5c15483ac5bb96e5c2e2e115bb0c0e1314837d77201bab37e8c03a13.65%
- a798def2cd3b2da331bf0b49cb69ac111edbadb206100eea1628ef3ef3e2e1bc11.64%
- f2c7d894abe8ac0b4c2a597caa6b3efe7ad2bdb4226845798d954c5ab9c9bf1510.8%
- cb41e9d0e8107aa9337dbd1c56f22461131ad0952a2472b4477e2649d16ecb158.76%
- 6f1c9b4c187669bc0371260d121caf48d65f829a9104c483befbd8fc0bed24f58.07%
- fb40ed0ffa6bc795923a941dab6b7d6b43583d0f152a6df4d8953d2c1a0cb4176.78%
- b8a91bec1fbb34606ed5326aad78af0d07c7915be86cfd595cc4c222504e98b16.67%
- 151189510070b06a3ecf5b6a8612cc45748676a579b9b4d877f5be3eb19710822.95%
- 50cbdbce85014f1042f99d5acdaad88ff268317a605bc3700b2487edd0f2ef0e2.53%
Process Ancestry
Top Grandparents
- smss.exe97.57%
- services.exe1.79%
- winlogon.exe0.43%
- wininit.exe0.17%
- cmd.exe0.02%
- svchost.exe0.02%
Top Parents
- smss.exe97.13%
- svchost.exe1.66%
- fontdrvhost.exe0.53%
- WUDFHost.exe0.15%
- LogonUI.exe0.1%
- winlogon.exe0.1%
- dwm.exe0.05%
- nvvsvc.exe0.02%
- nvwmi64.exe0.01%
- python.exe0.01%
Top Children
- conhost.exe100%
Security Analysis
What does csrss.exe normally do?
Runs from %SystemRoot%\System32\csrss.exe. One instance per Windows session (Session 0 + one per logged-in user). Protected process that cannot be terminated.
When is csrss.exe suspicious?
Running from any path other than System32. Unexpected number of instances. Parent process other than smss.exe lineage. Process can be killed (real csrss.exe is protected).
How do attackers abuse csrss.exe?
Frequently impersonated by malware using the same filename in temp/user directories. Real csrss.exe is a protected process; if you can attach a debugger to it, it is fake.
Detection guidance
Verify path is %SystemRoot%\System32\csrss.exe. Count instances (should equal number of sessions). Check that the process is marked as protected.
False positive notes
Multiple instances are normal in multi-session environments (RDP servers). Each session gets its own csrss.exe.
Related Processes
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