De­tect and serve

Australian T3 - - PLANE TRUTH -

Even if your name doesn’t ring alarm bells with Interpol, you will still be sub­jected to ever more ad­vanced searches to make sure that there’s noth­ing po­ten­tially lifethreat­en­ing stashed in your hand lug­gage.

Arch­way metal de­tec­tors (AMDs) have been stan­dard tech at air­ports for decades, but their so­phis­ti­ca­tion is now such that they can “de­tect the foil in a packet of cig­a­rettes”, ac­cord­ing to Rafi Sela, head of se­cu­rity at Tel Aviv’s Ben Gu­iron, dubbed “the world’s safest air­port”.

AMDs will also now be able to de­tect guns or knives made from a range of fer­rous, non-fer­rous metals and al­loys. Noth­ing is com­pletely fool-proof, though, and there are still ways to trick the tech­nol­ogy.

“If you take a piece of wire through in a closed cir­cle it will be de­tected,” says Sela, “but if you straighten it out, it’s un­likely to be. Also, if that closed loop of wire was par­al­lel to the ground, for ex­am­ple threaded through a

closed shirt col­lar, it would prob­a­bly pass through un­de­tected, too.”

It’s be­cause of these flaws that an x-ray team is re­quired, screen­ing around 180 people ev­ery sin­gle hour at in­ter­na­tional air­ports. Work­ing in teams of seven, in­clud­ing a cou­ple of “screen­ers”, who ro­tate on 20-minute shifts and an­a­lyse what’s seen on screen, flag­ging up bags that need to be checked.

“The x-ray im­age in­ter­prets the con­tents of each bag into dif­fer­ent colours,” ex­plains for­mer screener turned air­port se­cu­rity con­sul­tant Richard El­lis. “Or­ange is for or­ganic ma­te­rial like ex­plo­sives, liq­uids and gels; dark blue is for in­or­ganic ma­te­ri­als, such as gun metal, sharps, box cut­ters and IED (im­pro­vised ex­plo­sive de­vice) parts like wires; green rep­re­sents mixed ma­te­ri­als, from plas­tics to al­loys.” A screener also has to iden­tify the out­line of an ob­ject, which “in­cludes when they’re placed in a man­ner to con­fuse,” continues El­lis, “such as a gun stand­ing on its end to mask its pro­file.”

Im­ages have to be de­ci­phered in less than ten sec­onds dur­ing peak pe­ri­ods and even the x-ray ma­chine it­self will test the team of screen­ers ran­domly to en­sure they’re pay­ing at­ten­tion. Su­per­vi­sors can su­per­im­pose the im­age of a banned item – a Threat Im­age Pro­jec­tion (TIP) – on to any bag in the sys­tem to see if it’s picked up.

Se­cu­rity re­searcher and good-guy hacker Billy Rios warns that even safety mea­sures like these, in the wrong hands, could be po­ten­tially dan­ger­ous.

“TIPs could, the­o­ret­i­cally, be used to project the im­age of a le­gal item over a gun, knife or bomb part,” he ex­plains, “us­ing a ba­sic hacker tac­tic called an SQL in­jec­tion at­tack. This in­volves en­ter­ing a string of letters in the soft­ware to by­pass the su­per­vi­sor’s lo­gin and gain con­trol of the air­port’s bag­gage sys­tem.” The only way to guard against this, claims Rios, is to stop unau­tho­rised use of the ter­mi­nal and have a high turnover of new soft­ware.

The x-ray isn’t the last line of de­fence, though. Bag searchers also have the op­tion of cot­ton swab­bing any carry-on items. They do this with a por­ta­ble ma­chine that is ba­si­cally a low-level spec­trum an­a­lyzer, able to iden­tify the chemical sig­na­ture of bomb-mak­ing ma­te­ri­als and ex­plo­sives in sec­onds. Un­for­tu­nately, the ma­chine raises false pos­i­tives when it de­tects fer­til­iz­ers and heart medicines, so if you’re a farmer with a heart con­di­tion you may need to leave for the air­port a lit­tle early.

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