C#

[DllImport("advapi32.dll", SetLastError=true)]
static extern uint LsaEnumerateAccountRights(
       IntPtr PolicyHandle,
       IntPtr AccountSid,
       out string[] UserRights,
       out ulong CountOfRights);

AppDomain domain = Thread.GetDomain();
domain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);
IPrincipal p = Thread.CurrentPrincipal;
if(p.IsInRole("YourServiceRole"))
{
    // do something here.
}

private static readonly string domainName = System.Environment.UserDomainName;
private static readonly string userName = System.Environment.UserName;
private static readonly string fullUserName = domainName + @"\" + userName;
private static readonly WindowsPrincipal currentPrincipal =
    new WindowsPrincipal(WindowsIdentity.GetCurrent());


/// <summary>
/// Determines if user belongs to a given Windows user group name.
/// </summary>
/// <param name="groupName">Name of the user group to be checked.</param>
/// <returns>True if user belongs to the group.  Otherwise false.</returns>
public bool CheckUserGroup(string groupName)
{
    return currentPrincipal.IsInRole(domainName + @"\" + groupName);
}