Musings of an infosec nerd

Hunting Zebras (or how a toothbrush made me feel dumb)

  •   Mon 20 August 2012
  •   Random

Anyone who follows me to Twitter will probably remember that I've had some issues with my Samsung Galaxy S2 ever since I upgraded from 2.6  Froyo to 4.0.3 Ice Cream Sandwich. There are many posts in forums all about the battery and stability issues that have plagued this update and I have probably read all of them.

I also had some fun times with enabling encryption on the device due to it presenting a blank screen while it was performing the encryption rather that something that would let you know it was actually doing something.

With all the above issues I was hoping that the next update to arrive on my phone would solve all of my problems, so when Samsung made 4.0.4 available I installed it as soon as I could. Oh, and thanks Samsung for using OTA for the 4.0.4 update and not that piece of crapware you call Kies.

I bet you're wondering where the African wildlife and dental hygiene products are? Don't worry, they're coming.

I ran 4.0.4 for a few days and was very happy that my battery was lasting longer, without the infamous "Android OS" usage that was killing it last time. The phone was more stable, in the sense that it actually kept running instead of overheating and crashing twice a day. I'm also sure that it made me more attractive to the opposite sex, everything is coming up Ian...

Until I got a phone call. I don't know if I'm typical of a smartphone user in that I use my phone for 90% data such as email, IM, social networking, 8% SMS and about 2% voice as I make and receive phone calls quite rarely. Recently I have used voice a lot more as I am in the process of changing jobs to a new employer. This call was from my new boss. He sounded like he was verrrry verrry far away. The volume was so quiet that I assumed he was either using a speaker phone or hiding under a bed because Liam Neeson was hunting him. I punched the volume up button but he was still almost inaudible. I managed to make it though the phone call, and I just assumed that his phone was at fault...

Until I got another phone call from my Wife, she also sounded very far away. I know she never uses speaker phones and has done nothing to draw the eye of Liam Neeson so at that point I figured there was something wrong with my handset, and the only thing to chance recently was the OS.

I made a few calls to my network providers automated system and they were also quiet, so it is not just incoming calls that are a problem. Google is a wealth of information on this, apparently there were loads of problems like this on 2.6 and the solution was to enter a handset configuration mode and manually set the in call volume. I key in the special code and get to the configuration but the audio menu is blocked out so I can't make any changes. At this point I'm getting annoyed, why can't they test these updates before they send them out?

I start downloading apps that give access to "hidden" volume sliders, but all of them are set to maximum, I take a look at the internal logs and can't spot anything that might be causing the problem. The only thing I haven't done is a factory re-set. I hate doing these as it always takes me weeks to get my phone running just as I like it but at this point I need a phone that actually works as a phone. I bite the bullet and factory re-set the phone, selecting the option to back up all of my settings. 10 minutes later my phone is back to its ugly-ass default config, but at least all my settings have been preserved. I make a phone call to my network ... and it's really quiet again. Huh.

If you're still reading, I promise the ambulatory barcode is coming up.

I figure that maybe, just maybe the backup process kept a setting that is causing my problem so I factory re-set the phone again without taking a backup of any settings. Once test phone call later and it is still quiet. F*cksocks.

At this point I am convinced that I've either got a hardware issue with my earphone speaker or the software update has swapped all of my other problems for this show stopper. I'm making a lot of calls because of my new job, I've got to Liverpool this week to do a talk and I'm going to need to be contactable, damn it I'm going to have to dig out my old Desire and send this one back to Samsung for repair. This is just what I need!

I Google a little more to see if anyone else has seen this problem with 4.0.4 in particular and one of the long forum threads with all the usual "Do the handset configuration mode fix..." "Re-set the phone, you've got bad settings from 4.0.3" "Download these apps... root your phone...." had this little gem buried in the middle:

"I had this problem as well. It turned out my speaker grill was dirty. I cleaned it and it was fine after that"

Well that's just silly. This came on suddenly after my upgrade, it must be an issue with the software or a hardware failure. Still, doesn't hurt to try right? I grab my toothbrush and give the grill a little clean. I make a test call to my network and once agai.... hang on a second, that's loud again! I make another test call and it's back to normal!

I had forgotten the lesson that I thought I had learned years ago, before you go hunting for that rare Zebra that is causing your problem make sure your issue isn't with that simple looking horse that been standing there the whole time.

Hopefully the lesson has sunk in this time.

The personal blog of a UK based penetration tester