This article applies to PST Enterprise version 3.1 or higher.
PstPassword.exe is a tool used by the PstEnterpriseClient to examine PST files and circumvent password protection. This allows the PstEnterpriseClient to successfully process the PST file even if the PST file is password protected. PstPassword.exe does not modify the PST file in any way.
In some cases, Antivirus applications can classify legitimate software as a Trojan/Virus infection, such can be the case with PstPassword.exe. Although this file can be reported as a Trojan or Virus, it can be used without risk, so it is safe to create an exception rule or policy in your Antivirus application to allow PstPassword.exe.
You should, however, verify that the PstPassword.exe file is the one extracted and installed by the PST Enterprise installer package.