One reason for this is it only takes one person, with access to compromise a system and it's security.
Recently, Japan Today, disclosed that a policeman did just this by using P2P file sharing software:
Personal information on some 12,000 people related to criminal investigations has leaked onto the Internet from a computer of a Tokyo police officer via Winny file-sharing software, the Metropolitan Police Department said Friday. This is believed to be the largest volume of data leaked from the police on record, the department said.
Wikipedia lists the dangers of using this type of software, of which there are many:
- poisoning attacks (e.g. providing files whose contents are different from the description)
- polluting attacks (e.g. inserting "bad" chunks/packets into an otherwise valid file on the network)
- defection attacks (users or software that make use of the network without contributing resources to it)
- insertion of viruses to carried data (e.g. downloaded or carried files may be infected with viruses or other malware)
- malware in the peer-to-peer network software itself (e.g. distributed software may contain spyware)
- denial of service attacks (attacks that may make the network run very slowly or break completely)
- filtering (network operators may attempt to prevent peer-to-peer network data from being carried)
- identity attacks (e.g. tracking down the users of the network and harassing or legally attacking them)
- spamming (e.g. sending unsolicited information across the network- not necessarily as a denial of service attack)
Using any of these services, normally slows a computer down to a slow crawl. It can even destroy your computer.
Besides that, it's illegal to share copyrighted material (I think it's considered stealing). Not a very good situation for a policeman to get caught up in. What was he thinking?
Japan Today story, here.
Here is another post, I wrote about the murky world of P2P last year:
Attrition.org tracks how often information is compromised, and the reasons why, here.