Okay, Danger_MOOSE the n00b decker is hacking into the public library host on 44th and Wiltshire. MOOSE gets access immediately, since it's a public node. He then wishes to see what kind of system it's running. So, I uses an Analyze Host operation. MOOSE rolls his Computer of 3 + 3 hacking pool against the host's Control Rating (which MOOSE's player does not know yet) minus his Analyze utility's rating of 3. He rolls 3 net successes so MOOSE's checks the security (BLUE 3) and two subsystems, Control (

and Files (10). In reality the ACIFS of the host is (9/8/8/10/9) The host scored one success in the last test, so MOOSE's security tally is 1 (he does not know this, only the GM does. He can perform an Analyze Security operation if he wishes to know)
MOOSE wants to prove he's something so he decides to vandalize the online card catalog. He automatically finds the catalog because access is allowed to his anonymous account. He finds that the catalog has already been vandalized so he decides to change it himself. He performs a Vandalize Icon operation using his rating 5 redecorate utility. He rolls 3 computer + 3 hacking pool against a target number of 3 (8 Control - 5 redecorate utility) getting 4 successes the host rolls 3 dice against a target number of 4 ( [MOOSE's masking 4 + rating 4 Sleaze] /2) and gets 1 success. MOOSE gets 3 net successes so he can change three details of the icon. He decides to make it so all the cards in the virtual card catalog have a watermarked moose with the words DANGER beneath them.
Unknown to MOOSE (he failed his free Sensors test when logging on) another decker lies in wait. A matrix gang punk icon named Sloppy-Joseph ghosts up behind MOOSE and hits him with his Attack utility, a dirty sock swarming with flies. Sloppy rolls his computer 4 + 4 hacking pool against a target number of 3. 1,3,2,5,11,3,4. That's 6 successes, which stages his Light damage attack utility up by 3 levels to Deadly. MOOSE rolls his deck's Bod attribute (4) against a target number of 3 (Sloppy-Joseph's attack utility rating) minus his Armor utility rating. Since MOOSE has no armor utility active, he must roll against 3 because MOOSE logged in as a legitimate icon (big mistake, chummer). He rolls: 3, 2, 1, 10. His icon gets nearly smothered by the stinky sock. The simsense stench is nearly overwhelming. MOOSE must roll a Willpower test against a target number of five (his icon took serious damage) He passes the test and takes no overload damage. Now initiative is rolled and combat begins.
Had MOOSE had a better Sensor rating, he might have noticed the other decker in the first place. Even then, he should have attempted a Locate Decker before going straight to the target. Additionally, he never allocated any Hacking pool to detection factor, most likely because he was using it to make up for his lack of Computer skill. If his detection factor had been higher, the other decker may have never noticed him until the Vandalize Icon operation had finished and even then, he would have had to perform a locate Decker operation. MOOSE lost that cybercombat, but he got lucky, the other decker could have seeded that system with worms or used a BlackHammer utility and outright killed Danger_MOOSE.