Abstract: There is provided a method of maintaining a security risk level of data objects stored in a distributed system, comprising: estimating a current security risk level of at least one storage unit of each of a plurality of network nodes based on real time monitoring; distributing a plurality of data objects among the at least one storage units of the plurality of network nodes according to the current security risk level such that a minimal security requirement of each data object is complied with; detecting a change in the current security risk level of the at least one storage unit; and creating a new copy of at least one of the data objects for storage on a different network node such that the minimal security requirement of each data object is maintained.