Closing the loop

23 September 2013

I am probably a bit suspicious, but I always keep my credit card receipts, and check these off against the monthly statements. I have been doing this for at least 10 years. Mostly using GNUCash which makes the process of reconciling these pretty quick.

Over that time I have found a few mistakes, some in my favour, things that I have never been charged for, and a couple of things not in my favour. Like double charges for things, or fraudulent transactions, mostly these are easily rectified. Some of these have been identified by the Bank and rectified before I find them, sometimes not.

So the era of pay-wave where you generally don’t get a paper receipt is now coming. I personally have resisted this until I was asked by my employer to trial a new service. This allows me to receive a text message whenever a transaction meeting certain criteria is authorized.

The text messages are a huge peace of mind. This I have a record of every transaction, when it happens, including the place and amount. So I don’t feel the need to keep every receipt, and reconcile it to statements.

I hope this catches on and is used by many more banks.

Add Tracking

26 May 2013

There has been a lot of interest in the way in which advertisers gather the targeting information they use to target ads. The EFF has a detailed investigation into how facebook does this. This shows how your offline activities are used to refine the online advertisements that are shown by facebook. While this just covers facebook, many other sites use these companies and others to do similar things.

Personally I always use add blockers, back from the day when advertisers use animations and flashing to draw you eye, making it hard to read the content of the site. While this doesn’t prevent tracking it just cleans up my screen and makes the content readable.

I also came across this info-graphic that explains much of the on net tracking technology in a fairly understandable manner.

Internet Day Infographic

Linix demand for support

21 May 2013

If you talk to the Mobile operators they don’t support Linux. They say there is no demand. Well the interesting case in point is giffgaff. This MVNO network relies on the public to crowd source their support information on their network.

So with a bit of Goolge hacking we can see the number of support pages that mention Linix on the various networks:

So the level of Linux support provided by a small UK MVNO beats the mighty giants of the world mobile.

Internet Survey

27 March 2013

You may have heard of this elsewhere. This is a Grey Hat report from a anonymous individual, that has used a botnet to survey the entire IPV4 address space and perform a port scan on every one of those IP addresses.

In summary he delivered his scanning software to 30 thousand machines that provided a telnet port (23) that accepted a logon of either root/root root/(blank) admin/admin admin/(blank) or even (blank)/(blank). There were many more of these devices, but this was sufficient to his requirement to scan the entire IPv4 range in about 3 hours.

The main implication from this is the availability of these hosts could be used for DDoS and other botnet activities. One would speculate that they may be an increase in this type of activity going forward.

The Nexus 7 and Open Street Maps

26 October 2012

So with the launch of the mini iPad that is a lot of comparisons between this and the Goggle Nexus 7. I don’t have a iPad of any size and so don’t have any way of offering any sort of objective comparison. But what I do have is a Nexus 7 and the experience of using this while traveling around Europe.

We recently drove through Europe for a 2 week holiday. We skipped through France, Belgium, and Germany fairly quickly, as we wanted to visit Prague, and then go on down through Austria to Hungary. So Maps were very important for this.

We have a TomTom, not sure of the model, but has all of Europe in it. I have tried to update the maps in this but am not able to keep both sides of Europe as the size of the maps has expanded. TomTom only allow broad groups of countries to be loaded, so western Europe (UK, Germany, France, Spain, Portugal,…) or Eastern Europe (Czech Republic, Poland, Hungary,…). Not much use to us as we Live in the UK and often visit Hungary.

We also had paper map book, Michilln whole of Europe, OK for motorways, and getting a sense of the general direction, useless in cities and towns.

I also had the OSMAnd application on my Nexus 7. This is an open source application for viewing maps from The crucial feature needed when traveling is offline maps. OSMAND allows maps from each individual country to be downloaded, and can operate completely with no data connection.

Given the expense of GSM roaming in Europe, this is a feature that makes all the competition unusable. Goggle maps dose now allow downloaded data, but to use this feature you need to be in the location and then save the map tiles for that location. No pre-loading by country, and no offline searching, or route finding.

Here are a couple of scenarios where OSMAnd proved invaluable. First find the hotel we had booked. We had the address, and were in the approximate place, just needed to find the place. Putting the street name into Tom Tom showed a number of entries for the same street name, in different districts. This had no indication as to how far away and our limited knowledge of the city meant we didn’t know the districts. Searching for a street name in OSMAnd the matches are listed ordered by distance, either from the current location, or a location can be set. There is also a arrow giving an indication of direction.

Remember where we parked the car, not always easy if you are exploring. OK so I had a favorite location called Car, that I updated when we parked in a back street. Just get the nexus to get a fix, long tap on the current location, and save as a favorite. Then it was easy to find our way back to the backstreet where we parked.

Fancy a coffee? search from the current location for restaurants, add a filter “cafe”. This gives a nice list, showing direction and distance. Tap the map icon and the locations are highlighted on the map display. We found some wonderful breakfast cafes this way.

Traveling on some back roads we came to a line of traffic, it transpired that there was a major crash up ahead and we were not going to get through for quite a while. OSMAnd came out to find an alternative route, by taking some even more back road roads, that didn’t have any useful roadsigns.

This all relies on the quality and freshness of the data. generally this seemed to be pretty good. The listings of shops and businesses are pretty good in the larger towns, but small villages generally only had the street data there. The street data however was remarkably accurate.

USSD Code dialling exploits

28 September 2012

The recent disclosure of the finding that many phones respond to USSD dial strings in a tel: html markup without requiring any user input has recently been demonstrated.

The issue comes from the tel: html markup, that the phone will automatically execute a USSD command embedded in a tel link.

The Samsung S series has some powerful hidden codes, including one that will reset the phone to factory default *2767*3855#

The html string <iframe src=”tel:*%2306%23″/>  will display the IMEI, but if the code above is used this resets the phone. My experience suggests that most phones have secret codes that perform these sorts of actions. It only remains for these to be discovered for much wider exploitation.

Normally when a tel: prompt is encountered this just populates the dial number field and the user would then need to hit call to initiate the call. Some USSD codes do not require this, all phones should respond to the *#06# string with the IMEI of the phone.

Video of the presentation:

There is a test page: This is safe to go to as it only has the code to display your IMEI. If you visit this page on a phone browser, this page should open the dialler and pre-fill the dial string with *#06# ready for you to hit send. If your phone is vulnerable you will just see the IMEI displayed, that is the phone has immediately dialled this string.

Password databases and Salts

7 September 2012

I responded to a question on Stack Exchange

The purpose of a per record salt is to make the task of reversing the hashes much harder. So if a password database is exposed he effort required to break the passwords is increased. So assuming that the attacker knows exactly how you perform the hash, rather than constructing a single rainbow table for the entire database they need to do this for every entry in the database.

There is a separate issue with a database wide salt. This is a sort of key, and protects against the attacker using existing rainbow tables to crack the passwords. The database wide salt should be stored separately so that if the database is compromised then it is unlikely that the attacker will get this value as well.

The last area where many fail, is that there must be a way to change these salt values. If a security incident occurs we want to be able to change the salt values easily. So the database should have a salt version and the code will use the version to identify which salts to use and in what combination. When this is changed then a background task can update the database without taking the system off-line.


Get every new post delivered to your Inbox.

Join 365 other followers