The tools are said to have been created by the US National Security Agency (NSA), and accompanying documents appear to indicate a possible breach of the Swift global banking system.
Such a hack could have enabled the US to covertly monitor financial transactions, researchers said.
The files were released by Shadow Brokers, a hacking group that has previously leaked malware.
If genuine, it represents perhaps the most significant exposure of NSA files since the Edward Snowden leaks in 2013.