I recently encountered some news about the recently new Ransomware called CryptoDefense: it uses RSA 2048 to encrypt your valuables and offers the private key for a price. (It's already been solved since the private key is apparently cached locally)
My question however is how does this software actually encrypt large files of an arbitrary size such as photos and word documents that can be 1MB+ in file size with an RSA 2048 key? Is it actually RSA + AES or is it only using RSA 2048 by splitting files into small blocks somehow?
I've tried to find a detailed analysis of the software on Google by failed to find anything useful since almost all articles are fixated on it's insecure RSA mechanisms or bitcoin profits.