A total of 1,009 targeted email cyber-attacks hit Japanese companies and other institutions last year, the National Police Agency said Thursday.
The NPA arrived at the figure after analyzing information collected from around 4,900 companies and research organizations in the fields of defense and advanced technologies. Some cases led to leaks of information, according to the NPA.
Such attacks are becoming more sophisticated, the NPA warned, noting novel cases in which attackers exchange clean email messages with target entities before sending messages with viruses.
This particular style of attack was first seen in November and is still being used, the agency said.
In a typical case, an attacker contacts a target organization pretending to be a whistle-blower or job applicant. If the organization replies, the attacker then sends another email with a virus in an attached file labeled “Exposure Report” or “Resume.”
Antivirus software was not able to detect such viruses because the data were compressed and password-protected, the NPA said.
In one case, an attacker sent an email announcing the schedule of an inaugural news conference by Prime Minister Shinzo Abe soon after the change of government in December.
Amid heightened tensions between Japan and China over the Senkaku Islands, email messages were sent out by attackers pretending to be government officials.
Separately, a series of hacker attacks hit the websites of government agencies and courts last year, according to the NPA.
Two appear to have been carried out by Anonymous, an international group of hackers, while eight are believed to have been related to the friction between Japan and China.
The agency believes that most of the cyber-attacks were conducted from abroad. But it was unable to identify any suspect because of the difficulty for the Japanese police to investigate cybercrimes by foreign-based attackers.
The NPA said that users of file-sharing software decreased sharply last October when a revised copyright law took effect in which knowingly downloading illegal content, such as pirated movies, can be punished.
That month, the daily number of personal computers using file-sharing software averaged 68,864, down 33 percent from the preceding month, the NPA said.
Before the revision, only those posting illegal content were subject to punishment.