The Ask Partner Network (APN) was compromised for the second time in two months, as crooks found a way to deliver malware to computers running the Ask.com Toolbar. The first attack took place at the end of October and start of November 2016, and was detected by security researchers from Red Canary. The second took place in December, just after APN cleaned its network and revoked the digital certificate (issued in their name), which crooks used to sign the malicious update package. APN then issued a new digital certificate to sign future updates.
Source: https://www.bleepingcomputer.com/news/security/ask-com-toolbar-network-compromised-twice-in-two-months/