The Associated Press said the attempted hacks appeared to have been thwarted by threat-monitoring product.
The concern is revealed in the latest batch of Clinton's emails released by the State Department.
Director of National Intelligence James Clapper said his approach will be to "trust but verify."
The Department of Homeland Security needs to secure its own information systems better, according to an audit released on Tuesday.
The company also struck back at reports that the site had few female users.
Noel Biderman reaches a mutual agreement with Avid Life Media to step down.
Brian Krebs says a Twitter user Thadeus Zu had a link to the data early.
This is what it's like to be named Ashley Madison in the age of massive data leaks.
There is a $500,000 reward for information leading to the arrest of people involved in the hack.
Motherboard interviewed the hackers who call themselves the Impact Team.
Cyber security experts confirmed a second release of data stolen from AshleyMadison.com's parent company, Avid Life Media.
Media outlets are grappling with how much information to report from the data dump of AshleyMadison.com users’ sensitive information.
Hackers dump 9.7 gigabytes of data on dark web, including account and credit card details.
Nine people were indicted on charges of an insider trading scheme.
A cybersecurity expert says vehicle hacks could cause fatal accidents or lead to stolen personal data.
This hacking group has repeatedly accessed data that could be useful to Chinese counter-intelligence and internal stability.
The U.S. should urgently help Ukraine build its own defensible and independent communications system.