The website of Israel's main stock exchange was floored by a denial-of-service attack on Monday. Israeli airline El Al has also come under attack by hackers, but its website remains running despite the assault.
Visitors to the Tel Aviv stock exchange website are confronted with the message "Please try again later. The site is too busy right now", rather than the latest market information. Orna Goren, a stock exchange spokeswoman, told the BBC: "Our trading system is working as usual."
The attacks, unleashed by hackers affiliated with elements of Anonymous and other groups, are the latest in tit-for-tat campaign that began a fortnight ago. It began when a hacker called OxOmar posted thousands of Israeli credit card details online and invited others to make mischief with the information in order to wreck international trust in the cards' issuers.
Israeli deputy foreign minister Danny Ayalon responded to this by comparing the cyberattack to a terrorist assault and threatening reprisals. Elements of Anonymous waded in at this point, talking up attacks against Israeli websites. Pro-Israel hackers threatened to publish details of Saudi credit cards at around the same time.
OxOmar, who says he is part of a Saudi team but might be resident elsewhere, told YNet that a pro-Palestinian hacker group referring to themselves as "Nightmare" is leading the latest assaults. He also released a statement to a similar effect to Israel's Channel 10 TV channel (report in Hebrew, OxOmar's computer-generated recording is in English).
Palestinian political party Hamas, meanwhile, dished out encouragement from the sidelines.
Last week the Israeli Defence Ministry announced plans to establish a special cyber-warfare unit to monitor threats to the state online. ®