Jerusalem (CNN) -- The websites of the Tel Aviv Stock Exchange and of El Al, the Israeli airline, were brought down Monday morning by an apparent hacking attack.
An internet hacker who calls himself Ox Omar sent an e-mail to the Jerusalem Post Monday in which he claims that together with a hacking group calling themselves "Nightmare" that the websites of the Tel Aviv Stock Exchange and that of El Al would be brought down.
Idit Yaaron, the spokeswoman for the Tel Aviv Stock Exchange, told CNN that the main site of the stock exchange where the trading takes place was not harmed and operates on a very high level of Internet security. Trading has continued unaffected, she said. A secondary internet web site was affected for a short period of time.
El Al spokesman, Ran Rahav, released a statement saying, "El Al is aware that for the past two weeks a cyber war is raging against Israel. The company is closely monitoring the Saudi hacker activity. El Al is taking precautions regarding its website and as a result there may be disruptions in the activity of the website."
The "cyber war" started at the beginning of the month when a group claiming to be Saudi Arabian hackers posted the credit card information and other identifying data of thousands of Israelis on line, prompting an international investigation.
"Hi, It's Ox Omar from the group xp, largest Wahhabi group of Saudi Arabia" read a statement posted on an Israeli sports web site the group hacked into. "We are anonymous Saudi Arabian hackers. We decided to release (the) first part of our data about Israel." Wahhabism is an Islamic religious movement.
The Bank of Israel released a statement last Tuesday saying that, based on information from credit card companies, only around 15,000 credit card numbers were exposed and those credit cards were blocked for use in Internet and phone purchases.
Yoram Hacohen, who heads the Israeli Law, Information and Technology Authority at the Israeli Ministry of Justice, told CNN in a phone interview on Friday that he is more concerned about the private information that was released than the actual credit card numbers; he fears that the publishing of e-mail addresses, phone numbers and home addresses could lead to identification theft.
Hacohen said that hacking is a criminal act against citizens and the Israeli authorities have begun a criminal investigation, including a computer forensic probe to search for electronic evidence in an attempt to locate the group. The theft of personal information is a criminal act under Israel's Privacy Protection law.
Hacohen acknowledged that in the digital world, offenders are difficult to track and authorities are asking for international help in the matter.
Israeli Deputy Foreign Minister Danny Ayalon, speaking at a public event, called the Saudi hackers attack "a breach of sovereignty comparable to a terrorist operation and (it) must be treated as such." A few days later his own website was targeted in a cyber attack. In a statement on his Facebook page, Ayalon wrote that "Muslim extremists" hacked into his website "to try and prevent me from continuing to do my work on behalf of the State of Israel, especially my online public diplomacy.
Prime Minister Benjamin Netanyahu created a National Cyber Directorate in 2011, noting the emergence of cyber attacks that could "potentially paralyze life systems -- electricity, communications, credit cards, water, transportation, traffic lights."
He said in December that the new agency -- along with a rocket defense system and a physical fence -- would help protect Israel against its enemies.