Potential MOVEit Transfer CVE-2023-34362 Exploitation - Dynamic Compilation Via Csc.EXE — Detection Rule
Detects the execution of "csc.exe" via "w3wp.exe" process. MOVEit affected hosts execute "csc.exe" via the "w3wp.exe" process to dynamically compile malicious DLL files. MOVEit is affected by a critical vulnerability. Exploited hosts show evidence of dynamically compiling a DLL and writing it under C:\\Windows\\Microsoft\.NET\\Framework64\\v4\.0\.30319\\Temporary ASP\.NET Files\\root\\([a-z0-9]{5,12})\\([a-z0-9]{5,12})\\App_Web_[a-z0-9]{5,12}\.dll. Hunting Opportunity Events from IIS dynamically compiling binaries via the csc.exe on behalf of the MOVEit application, especially since May 27th should be investigated.