func (v *validator) ValidateSignature(auth kolide.Auth) (kolide.Auth, error) {
	info := auth.(*resp)
	status, err := info.status()
	if err != nil {
		return nil, errors.New("missing or malformed response")
	}
	if status != Success {
		return nil, errors.Errorf("response status %s", info.statusDescription())
	}
	decoded, err := base64.StdEncoding.DecodeString(info.rawResponse())
	if err != nil {
		return nil, errors.Wrap(err, "based64 decoding response")
	}
	doc := etree.NewDocument()
	err = doc.ReadFromBytes(decoded)
	if err != nil || doc.Root() == nil {
		return nil, errors.Wrap(err, "parsing xml response")
	}
	elt := doc.Root()
	signed, err := v.validateSignature(elt)
	if err != nil {
		return nil, errors.Wrap(err, "signing verification failed")
	}
	// We've verified that the response hasn't been tampered with at this point
	signedDoc := etree.NewDocument()
	signedDoc.SetRoot(signed)
	buffer, err := signedDoc.WriteToBytes()
	if err != nil {
		return nil, errors.Wrap(err, "creating signed doc buffer")
	}
	var response Response
	err = xml.Unmarshal(buffer, &response)
	if err != nil {
		return nil, errors.Wrap(err, "unmarshalling signed doc")
	}
	info.setResponse(&response)
	return info, nil
}
This attack-focused weakness is caused by improperly implemented authentication schemes that are subject to spoofing attacks.