The internal document -- which was first reported by The Washington Post -- identified the firms as either exclusively Afghan or as joint ventures with international companies.
CNN reporting comes from an independent source, familiar with the contents of the report.
The companies were later identified as "high-risk" firms, having subcontracted out to smaller entities without sufficient accounting measures, the source said.
In one instance, $7.4 million was transferred into the bank account of a "low-level police officer."
After a series of transactions, including multiple withdraws, officials then traced $3.3 million in weapons, explosives and cash transfers "to the enemy," the source said.
An small army of intelligence analysts, law enforcement officers, lawyers, auditors and forensic accountants mapped out an interlocking network of trucking contractors, and their dealings with dozens of subcontractors.
Some were only "profiteering," the source said, likely without a clear understanding of where some of the funds delivered.
The contract program, called Host Nation Trucking -- which expires in September -- has since been replaced by a more stringent system that requires up to 40 different contractors -- an effort to reduce overall reliance on a single firm.
The new program is also meant to tighten accounting measures of second and third party vendors, an area various groups had previously been able to exploit, the source said.
"When you have the extent of corruption we may have seen with these contracts, that's clearly not acceptable and they have to change the way they are doing business," Lisa Curtis, a senior fellow at the conservative Heritage Foundation, told CNN.
"But ... it's unrealistic to think something like this would not happen given the influence of the Taliban, the fact that they are intimidating the population every day," Curtis added.
Government officials are currently pursuing corrective actions against the trucking firms, including suspensions and limits on work, though all eight companies still remain on the U.S. payroll.