Via Bruce Schneier (and other sources), the Australian government suffered one of its worst-ever disclosures of secrets caused by not looking through used furniture:
It begins at a second-hand shop in Canberra, where ex-government furniture is sold off cheaply.
The deals can be even cheaper when the items in question are two heavy filing cabinets to which no-one can find the keys.
They were purchased for small change and sat unopened for some months until the locks were attacked with a drill.
Inside was the trove of documents now known as The Cabinet Files.
The thousands of pages reveal the inner workings of five separate governments and span nearly a decade.
Nearly all the files are classified, some as "top secret" or "AUSTEO", which means they are to be seen by Australian eyes only.
But the ex-government furniture sale was not limited to Australians — anyone could make a purchase.
And had they been inclined, there was nothing stopping them handing the contents to a foreign agent or government.
The found documents ranged from embarrassing (to both major Australian parties) to seriously top secret (troop deployments, police investigations). In response, the Australian government is calling for increased penalties for publishing or even possessing secret documents—but as Schneier points out, in this case that would have made the breech immeasurably worse for Australia:
This illustrates a fundamental misunderstanding of the threat. The Australian Broadcasting Corp gets their funding from the government, and was very restrained in what they published. They waited months before publishing as they coordinated with the Australian government. They allowed the government to secure the files, and then returned them. From the government's perspective, they were the best possible media outlet to receive this information. If the government makes it illegal for the Australian press to publish this sort of material, the next time it will be sent to the BBC, the Guardian, the New York Times, or Wikileaks. And since people no longer read their news from newspapers sold in stores but on the Internet, the result will be just as many people reading the stories with far fewer redactions.
In all, it's a reminder of the security adage that no security system can completely protect against human stupidity.