Thus far Israeli credit card companies have said that 25,000 numbers were released online. The hacker, who goes by the name of OxOmar, claims to have leaked the information of more than 400,000 Israelis-- and says the "Jewish lobby" is hiding the extent of the attack.
Reuters reports this is one of the worst attacks of its kind Israel has ever faced and that concerns are "heightened" because of the potential use of stolen information by Israel's enemies.
"These matters are worrisome," Science and Technology Minister Daniel Hershkowitz told Israel Radio, calling the incident "a sample of the great danger out in cyberspace."
On the back of the credit card theft, a parliamentary committee has scheduled a session for the coming week to review Israel's readiness to defend itself from cyber attacks.
"We must prepare to cope with cyber threats in anticipation of any attempts to use Internet terror to strike at Israel," said lawmaker Ronit Tirosh, the committee chairwoman.
Some newspaper columnists speculated that hackers might be retaliating for recent attacks in Iran, including the mysterious Stuxnet computer virus that snarled its controversial nuclear computer systems.
CNN reports an international investigation to locate the hackers (which it describes as "group") has begun. From the several reports I've read, there's no firm evidence thus far the cyber attack originates from Saudi Arabia.
It's hard to gauge the extent of the attack or the repercussions at this juncture, but the implications could be immense.
Yoram Hacohen, the head of the Israeli Law, Information and Technology Authority at the Israeli Ministry of Justice, told CNN in a phone interview Friday he's more concerned about the private information that was released, not the credit card numbers....The publishing of information such as e-mail addresses, phone numbers, home addresses and passwords could lead to identification theft, he said... some of the information exposed belongs to Jews worldwide, not only Israelis.
Israeli authorities have begun a criminal investigation, including a computer forensic probe to search for electronic evidence to try to locate the group, Hacohen said. The theft of personal information is a criminal act under Israel's Privacy Protection Law.
He acknowledged that in the digital world, offenders are very difficult to track, and authorities are asking for international help in the matter.
"The peculiar incident we are facing could be a bad joke, a youthful prank, a hate-driven terror attack for beginners or the cellars of the Iranian intelligence in Tehran," wrote Israeli columnist Ben Caspit in the Maariv newspaper Friday, outlining the difficulties of trying to identify the hackers.