Use WMI for resolving the SID:
Set wmi = GetObject("winmgmts://./root/cimv2")
groupname = "..."
qry = "SELECT * FROM Win32_Group WHERE Name='" & groupname & "'"
For Each group In wmi.ExecQuery(qry)
sid = group.SID
Next
If Not IsEmpty(sid) Then
WScript.Echo "Group " & groupname & " has SID " & sid & "."
Else
WScript.Echo "SID For group " & groupname & " could not be resolved."
End If
If you need to convert the binary SIDs used in AD I'd suggest you do something like this:
Function DecodeSID(binSID)
ReDim octets(LenB(binSID))
'convert binary string to octet array
For i = 1 To LenB(binSID)
octets(i-1) = AscB(MidB(binSID, i, 1))
Next
'convert octet array to SID string
sid = "S-" & CStr(octets(0)) & "-" & Octet2Str(Array(octets(2), octets(3), _
octets(4), octets(5), octets(6), octets(7)))
For i = 8 To (4 * octets(1) + 4) Step 4
sid = sid & "-" & OctetArrayToString(Array(octets(i+3), octets(i+2), _
octets(i+1), octets(i)))
Next
DecodeSID = sid
End Function
Function OctetArrayToString(arr)
v = 0
For i = 0 To UBound(arr)
v = v * 256 + arr(i)
Next
OctetArrayToString = CStr(v)
End Function
For more information on binary SIDs see here.