A landing zone (or LZ) is a space where helicopters can land to deploy or extract troops. In Vietnam, when they needed an LZ, they would deploy items such as fuel-air bombs and Agent Orange to clear out large circles of vegetation. This allowed the helicopters to land without hitting any trees.

Another use for the term landing zone concerns hard drives. Older drives that relied on stepper motors required the heads to be parked. The area on the drive that was used to park the head became known as the landing zone or parking cylinder. This procedure placed the heads on an unused area of the drive, away from data. This helped to reduce the danger of data loss if the drive was accidently bumped.

Newer drives use voice-coil actuators with self-parking heads. You no longer have to run a parking program before shutting down your computer.

A device used to increase the success rate of a buffer overflow attack when an exact location in memory cannot be calculated

When exploiting a buffer overflow to execute inserted code, it is not always possible to know exactly where the buffer (and therefore the malicious code) is in memory, meaning that the new return address may not actually point to the inserted code. However, if the inserted code is large enough, the return address will probably point to some part of it.

So, if we pad the start of the code with instructions that do nothing relevent to the program (NOP, LDI, etc.), then it's likely that the processor will jump to somewhere in this landing zone, and proceed through it doing nothing of interest until it gets to the inserted code proper.

The most successfull landing zone is one constructed of single word instructions, so there is no chance of the processor jumping to (and executing) an operand with unpredictable results. Unfortunately, packets full of (NOPNOPNOPNOPNOPNOP) are a dead giveaway to intrusion detection systems, which can filter out the packet and alert the administrator.

The concept of a landing zone was first published in Aleph One's smashing the stack for fun and profit.

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