[anw_1]
Name             = Max Mustermann
Zeit1            = 14:37
Zeit2            = 18:25
Gesamtstunden    = 4
 
[anw_2]
Name             = Max Mustermann
Zeit1            = 14:37
Zeit2            = NULL
Gesamtstunden    = NULL
 
[anw_3]
...

For Each person As String In WertLesen(pfad-zur-inidatei, vbNullString, _
  vbNullString)
 
     If WertLesen(pfad-zur-inidatei, person, "Zeit2") = "NULL" Then
           WertSchreiben(pfad-zur-inidatei, person", "Zeit2", _
           Format(Now, "HH:mm")
     Else
     End If
 
Next

WertLesen(PFAD AS STRING, SEKTION AS STRING, SCHLUESSEL AS STRING)
WertSchreiben(PFAD AS STRING, SEKTION AS STRING, SCHLUESSEL AS STRING, WERT AS _
  STRING)