Distributed machine learning has been widely used in recent years to tackle
the large and complex dataset problem. Therewith, the security of distributed
learning has also drawn increasing attentions from both academia and industry.
In this context, federated learning (FL) was developed as a "secure"
distributed learning by maintaining private training data locally and only
public model gradients are communicated between. However, to date, a variety of
gradient leakage attacks have been proposed for this procedure and prove that
it is insecure. For instance, a common drawback of these attacks is shared:
they require too much auxiliary information such as model weights, optimizers,
and some hyperparameters (e.g., learning rate), which are difficult to obtain
in real situations. Moreover, many existing algorithms avoid transmitting model
gradients in FL and turn to sending model weights, such as FedAvg, but few
people consider its security breach. In this paper, we present two novel
frameworks to demonstrate that transmitting model weights is also likely to
leak private local data of clients, i.e., (DLM and DLM+), under the FL
scenario. In addition, a number of experiments are performed to illustrate the
effect and generality of our attack frameworks. At the end of this paper, we
also introduce two defenses to the proposed attacks and evaluate their
protection effects. Comprehensively, the proposed attack and defense schemes
can be applied to the general distributed learning scenario as well, just with
some appropriate customization.