An Australian university has discovered a major flaw in wireless standards that, if exploited, can jam wireless networks within five seconds.

The vulnerability, found in IEEE 802.11 standards, allows hackers using basic equipment to block wireless networks within of one kilometre, according to research from Queensland University of Technology's Information Security Research Centre, Australia.

Until now, wireless denial-of-service attacks required high-power antennas, but the new attack will make network jamming easier, the researchers said.

The vulnerability exists in hardware that uses a Direct Sequence Spread Spectrum (DSSS) physical layer, which includes IEEE 802.11, 802.11b and 802.11g devices.