As to who is behind this attack and how they infected the official versions of CCleaner, Talos hasn't released anything yet, and Yung isn't providing any other details.
UPDATED Sept. 21: Further analysis of the malware injected into the CCleaner updater, and the malware's command-and-control servers, strongly indicates that the CCleaner hack was an attempt at industrial espionage.
If a machine was infected by CCleaner, a new Cisco report says, the command-and-control server would check whether the infected machine happened to on the internal network of any one of the technology companies on a target list that included Google, Cisco, Samsung, Sony, Epson, D-Link, HTC, Linksys and others. The server would then deliver a "backdoor" to the infected machine for further exploitation.
No Chinese or Russian companies were on the target list."




