Scores of these civilian targets constitute Israel's "soft underbelly" since they are not covered by government efforts to protect critical infrastructure, including military and security installations, says Gabi Siboni, program director of the Institute for National Security Studies' cyberwarfare program.
"Cyberdefense in the civilian arena is not being dealt with, in contrast to the defense sector, including defense industries, and scores of critical national infrastructures which receive regular guidelines on the issue from government departments," he told the business daily Globes.
"But telecommunications carriers, including Internet service providers and other entities with systems, which, if attacked, are liable to substantially disrupt service to a large clientele, are not defined by the government as critical infrastructures, and there's no authority [that] directs them how to prepare against a possible cyberattack.
"While dozens of critical national infrastructures are protected, someone deciding on an attack will prefer to focus his efforts on the soft underbelly, against those who are unprotected," Siboni said.
"The target could be the water company of a large city. Today, water companies and critical entities in the economy are not protected for such a situation because no one demands that they should be prepared."
Siboni's warning, which he will present at an INSS conference this week on the financial industry's preparedness for a cyberstrikes, comes amid major efforts by U.S., European and other governments to erect cyberdefenses around a comprehensive range of critical civilian infrastructure as the danger of crippling cyberattacks grows.
Recent disclosures of extensive electronic eavesdropping by U.S. intelligence on agencies of the European Union and other allies, including diplomatic missions, have heightened international concerns about the perils of cyberattacks.
The Financial Times said last week Europe "should transform itself into a data protection fortress."
Israel, which along with the United States has engaged Iran in an ongoing cyberwar largely aimed at sabotaging Tehran's nuclear program, has been in the forefront of building up cyberdefenses as the Iranians have struck back.
Prime Minister Binyamin Netanyahu has sought to accelerate the construction of these defenses, and says the Jewish state is hit by hundreds of cyberstrikes every month.
Syrian government loyalists have joined the onslaught in recent months as Israel has mounted airstrikes against Hezbollah targets in Syria amid the country's civil war.
On May 25, Israeli officials disclosed there had been a failed attack two weeks earlier on the water system in the northern city of Haifa, a major port and naval base. They said the attack originated in Syria in apparent retaliation for an Israeli airstrike earlier that month.
Yitzhak Ben-Yisrael, chairman of the National Council for Research and Development, said critical Israeli infrastructure such as the electricity and water industries and the stock exchange undergo hundreds of cyberattacks every week.
"The number of cyberattacks is huge," he said. "We're talking about an attack every moment. We have to constantly think about the upcoming threats."
In June, Netanyahu reported "a significant increase in the scope of cyberattacks on Israel by Iran. ... The targets are our vital national systems.
"In effect, aside from electricity, water, the railways and banks, every area that's open in economic life, not to mention defense, is a potential target for cyberattacks."
Netanyahu's previous government established a national cybercenter to help coordinate with the military and intelligence services to counter cyberattacks.
"Today, cyber is part of the battlefield," he declared. "This is not tomorrow's warfare -- it's already here today."
Iran, which has been on the receiving end of U.S. and Israeli cyberstrikes beginning with the notorious Stuxnet virus that crippled part of Tehran's uranium enrichment program in 2009-10, has been making a determined effort to enhance not only its cyberdefenses but its offensive capabilities as well.
A key catalyst for boosting cyberdefenses in the United States and its allies were two recent high-profile attacks, one against Saudi Arabia's oil industry, blamed on Iran, and an alleged North Korean attack on banks and media companies in South Korea.