The targeted phishing attack also allowed the attacker to gain access to all files in ICANN's Centralized Zone Data System (CZDS), a centralized point for interested people to request access to so-called zone files provided by participating top level domains. ICANN gave notice of the breach Tuesday, though the CZDS aspect of the compromise was discovered earlier this month.
The CZDS compromise included email and postal addresses, telephone numbers, user names and passwords of some users of the organization's services, although the passwords were stored as salted cryptographic hashes. ICANN recommends that CZDS users take steps to protect online accounts for which they used the same user names or passwords, and the organization is providing notices to users whose personal information may have been compromised.
ICANN, the coordinator of the Internet's Domain Name System, believes the targeted phishing attack started in late November. The attack included email messages "crafted to appear to come from our own domain being sent to members of our staff," ICANN said in a press release.
The attackers also gained access to ICANN's Governmental Advisory Committee's Wiki, including some public information, a members-only index page, and one user's profile page. The attackers also accessed user accounts on the ICANN blog and the ICANN WHOIS information portal, but there was no other impact on those systems.
Based on ICANN's investigation so far, the organization is not aware of any other systems that were compromised. This year, ICANN began rolling out security enhancements across the organization, and it has taken additional steps since discovering the attack, it said.
"We are providing information about this incident publicly, not just because of our commitment to openness and transparency, but also because sharing of cybersecurity information helps all involved assess threats to their systems," ICANN said.
Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's email address is grant_gross@idg.com.