Please spend three minutes and look up the terms:
Hard money
Federal Elections Commission reporting requirements
Limits on campaign contributions
Perjury
If these contributions were coming from random IP botnet locations, they have to falsely declare who the contribution is from. They must provide a name and address and phone number and industry for each contribution. All of them will be reported and very easy to discover if they fabricated the information.
Further, the person who compiles the FEC statements has to certify it under penalty of perjury. That means if they saw 30,000 donations from Joe Person at 123 Main Street in 29,000 different zip codes, they would be guilty of perjury if they tried to file that campaign finance statement.
Finally, and one last time: All Soros has to do is write a check to any soft money source for any amount he desires. To do what you suggest would be so incredibly stupid as it would be a criminal conspiracy to commit a federal felony; he and everyone associated with it would face stiff federal penalties.
Hillary, Lois Lerner , Obama ,Soros have committed countless crimes and are basically above the law.
What is a little perjury to Democrats?
It would be no problem at all to generate 200,000 different names - all with legitimate addresses and a selection of different legitimate credit cards.
Feed the input file into a botnet script at a controlled rate and transfer whatever funds the sponsors wish to spend.
The certifying authority would never need to know, and it would not be obvious unless you started checking the credit cards. They would not check them. But if anyone ever did, the campaign authorities would have plausible deniability.
And if they succeeded in overturning the election, there would never be any follow-up.