Attacks, such as MITM and DoS attacks, on a distributed computing system may be detected by sending a work assignment to an execution device through a first communication channel. A report may then be received through a second communication channel of the work assignment received by the execution device. Information regarding the received work assignment may then be in view of information regarding the sent work assignment to determine whether an error, such as an MITM or DoS attack, has occurred. If the analysis indicates that the report does not include the sent work assignment, then a DoS attack may have occurred. If the analysis indicates that the work assignment received by the recipient does not correspond to the sent work assignment, then a MITM attack may have occurred. If an error has occurred, an indication might be recorded and/or other types of actions might also be taken.