runas - create new SYTEM token for become (#83827)

Instead of re-using the token used in impersonation, this change will
create a new token for the SYSTEM account as returned by LogonUser. The
benefits of this is that the token will contain the full privileges for
the SYSTEM account rather than potentially one that has restricted
privileges we used during impersonation. It should also help avoid
problems on Windows that fails on status 0x0000016F when the
impersonated token during become was from a process that is restricted
from creating sub processes.

2 files changed, 18 insertions, 25 deletions

diff --git a/changelogs/fragments/become-runas-system.yml b/changelogs/fragments/become-runas-system.yml
new file mode 100644
index 0000000000..2ad7e46562
--- /dev/null
+++ b/changelogs/fragments/become-runas-system.yml
@@ -0,0 +1,4 @@
+bugfixes:
+  - ->
+    runas become - Generate new token for the SYSTEM token to use for become. This should result in the full SYSTEM
+    token being used and problems starting the process that fails with ``The process creation has been blocked``.
diff --git a/lib/ansible/module_utils/csharp/Ansible.Become.cs b/lib/ansible/module_utils/csharp/Ansible.Become.cs
index d3bb1564fa..68d4d11d7a 100644
--- a/lib/ansible/module_utils/csharp/Ansible.Become.cs
+++ b/lib/ansible/module_utils/csharp/Ansible.Become.cs
@@ -333,13 +333,12 @@ namespace Ansible.Become
                 // Grant access to the current Windows Station and Desktop to the become user
                 GrantAccessToWindowStationAndDesktop(account);
 
-                // Try and impersonate a SYSTEM token, we need a SYSTEM token to either become a well known service
-                // account or have administrative rights on the become access token.
-                // If we ultimately are becoming the SYSTEM account we want the token with the most privileges available.
-                // https://github.com/ansible/ansible/issues/71453
-                bool mostPrivileges = becomeSid == "S-1-5-18";
+                // Try and impersonate a SYSTEM token. We need the SeTcbPrivilege for
+                //  - LogonUser for a service SID
+                //  - S4U logon
+                //  - Token elevation
                 systemToken = GetPrimaryTokenForUser(new SecurityIdentifier("S-1-5-18"),
-                    new List<string>() { "SeTcbPrivilege" }, mostPrivileges);
+                    new List<string>() { "SeTcbPrivilege" });
                 if (systemToken != null)
                 {
                     try
@@ -357,11 +356,9 @@ namespace Ansible.Become
 
             try
             {
-                if (becomeSid == "S-1-5-18")
-                    userTokens.Add(systemToken);
                 // Cannot use String.IsEmptyOrNull() as an empty string is an account that doesn't have a pass.
                 // We only use S4U if no password was defined or it was null
-                else if (!SERVICE_SIDS.Contains(becomeSid) && password == null && logonType != LogonType.NewCredentials)
+                if (!SERVICE_SIDS.Contains(becomeSid) && password == null && logonType != LogonType.NewCredentials)
                 {
                     // If no password was specified, try and duplicate an existing token for that user or use S4U to
                     // generate one without network credentials
@@ -384,6 +381,11 @@ namespace Ansible.Become
                     string domain = null;
                     switch (becomeSid)
                     {
+                        case "S-1-5-18":
+                            logonType = LogonType.Service;
+                            domain = "NT AUTHORITY";
+                            username = "SYSTEM";
+                            break;
                         case "S-1-5-19":
                             logonType = LogonType.Service;
                             domain = "NT AUTHORITY";
@@ -426,7 +428,7 @@ namespace Ansible.Become
         }
 
         private static SafeNativeHandle GetPrimaryTokenForUser(SecurityIdentifier sid,
-            List<string> requiredPrivileges = null, bool mostPrivileges = false)
+            List<string> requiredPrivileges = null)
         {
             // According to CreateProcessWithTokenW we require a token with
             //  TOKEN_QUERY, TOKEN_DUPLICATE and TOKEN_ASSIGN_PRIMARY
@@ -436,9 +438,6 @@ namespace Ansible.Become
                 TokenAccessLevels.AssignPrimary |
                 TokenAccessLevels.Impersonate;
 
-            SafeNativeHandle userToken = null;
-            int privilegeCount = 0;
-
             foreach (SafeNativeHandle hToken in TokenUtil.EnumerateUserTokens(sid, dwAccess))
             {
                 // Filter out any Network logon tokens, using become with that is useless when S4U
@@ -449,10 +448,6 @@ namespace Ansible.Become
 
                 List<string> actualPrivileges = TokenUtil.GetTokenPrivileges(hToken).Select(x => x.Name).ToList();
 
-                // If the token has less or the same number of privileges than the current token, skip it.
-                if (mostPrivileges && privilegeCount >= actualPrivileges.Count)
-                    continue;
-
                 // Check that the required privileges are on the token
                 if (requiredPrivileges != null)
                 {
@@ -464,22 +459,16 @@ namespace Ansible.Become
                 // Duplicate the token to convert it to a primary token with the access level required.
                 try
                 {
-                    userToken = TokenUtil.DuplicateToken(hToken, TokenAccessLevels.MaximumAllowed,
+                    return TokenUtil.DuplicateToken(hToken, TokenAccessLevels.MaximumAllowed,
                         SecurityImpersonationLevel.Anonymous, TokenType.Primary);
-                    privilegeCount = actualPrivileges.Count;
                 }
                 catch (Process.Win32Exception)
                 {
                     continue;
                 }
-
-                // If we don't care about getting the token with the most privileges, escape the loop as we already
-                // have a token.
-                if (!mostPrivileges)
-                    break;
             }
 
-            return userToken;
+            return null;
         }
 
         private static SafeNativeHandle GetS4UTokenForUser(SecurityIdentifier sid, LogonType logonType)