// This is where we'll save the attachment
var tablename   = 'incident';
var recordSysId = '8d6353eac0a8016400d8a125ca14fc1f';
var filename    = 'snlogo.png';

// Let's download the ServiceNow Logo
var logoUrl = 'https://instance.service-now.com/images/logos/logo_service-now.png';
var request = new sn_ws.RESTMessageV2();
request.setHttpMethod('get');
request.setEndpoint(logoUrl);

// Configure the request to save the response as an attachment
request.saveResponseBodyAsAttachment(tablename, recordSysId, filename);

// When we execute the request, the attachment will automatically be
// saved to the record we specified
var response = request.execute();
var httpResponseStatus = response.getStatusCode();
var httpResponseContentType = response.getHeader('Content-Type');
gs.debug("http response status_code: " + httpResponseStatus);
gs.debug("http response content-type: " + httpResponseContentType);

// Get the sys_id of the newly created attachment
var newAttachmentSysId = response.getResponseAttachmentSysid();

// Do something useful with it
var grAttach = new GlideRecord('sys_attachment');
if (grAttach.get(newAttachmentSysId)) {
  // Note: we're using the scoped version of GlideSysAttachment 
  // for this example. 
  var gsa = new GlideSysAttachment()
  var content = gsa.getContent(grAttach); 
  // Now we have the data...the rest is up to you
}