218 Chapter8·Fuzzing been modified. In some cases application developers have implemented these check- sums as a means to prevent their applications from being fuzzed. This is a dangerous and likely ineffective way to prevent malicious data from being submitted to an appli- cation. If an attacker is able to generate the checksum for their malicious data, they will be able to bypass these checks. While it may be possible for the fuzzing framework to generate these checksums, it is unlikely that it will be an efficient use of resources. Instead the checksum routines can be bypassed or modified so that they always confirm the validity of data. Preparing for External Interaction We'll now discuss steps to take for preparing for an external interaction. Taking the Snapshot Taking the snapshot is a simple task with VMware Workstation. To take a snapshot on VMware Workstation, get the machine in a state to begin fuzzing. Then click on the "Take a snapshot of the virtual machine" button highlighted in Figure 8.3.