iPhone Forensics – Part 1

As with anything else its important to really understand the inner working of the iPhone before attempting to recover any data from it, as two things may happen: the device may be rendered useless or the data on it become contaminated which is just as bad when you are looking for evidence.

The iPhone runs a custom version of Mac OS X 10.5 (Leopard) with several differences which include:

  1. an ARM architecture as opposed to the Intel x86 architecture used on desktop machines
  2. special hardware including an accelerometer, proximity sensor, multi-touch capable screen and several radios including GSM, Wi-Fi and Bluetooth
  3. a user interface framework built around the iPhone to accommodate the proprietary hardware
  4. a signed kernel designed to prevent tampering

What can be recovered:

Information stored on the iPhone includes keyboard caches containing usernames, passwords, searches, and some history of what was ever typed on the phone.

Sections of map images from the phone’s Google Maps application, location searches and their coordinates can be found on the phone.

Browser cache and deleted items identifying what websites the user has visited.

Deleted voicemails, email and SMS messages can also be recovered.

A cache of screenshots of the user’s last activities which are kept to improve the experience of opening and closing applications.

Deleted images, address book entries, contacts, calendar events and other personal information can be recovered.

A very detailed call history list beyond what is visibly on the iPhone as well as deleted items from the history.

Disk Layout:

The iPhone uses a solid state NAND flash which is treated as a disk by storing a partition table and a formatted file system. Generally the iPhone will be configured with 2 partitions as shown below.

The first partition is the root which houses the operating system and all the preloaded applications on the iPhone. This partition is read-only and designed to stay like that. The size of the root partition varies depending on the version of the phone (size of the flash).

The remaining space is assigned to the user and is mounted as /private/var as shown above. This allows Apple to upgrade firmware of the devices without in theory touching the user data on the device.

To perform forensics on this type of environment we would need to make the root partition writable  to install forensics software in order to maintain the integrity of the data on the user’s data partition.


The iPhone can communicate in multiple ways including the serial port, 802.11 Wi-Fi and Bluetooth. AFC or Apple File Connection is a serial protocol used by iTunes to connect to the iPhone and transfer everything from music to software upgrades.

iTunes is not allowed access to the whole iPhone but is rather placed in a jailed environment. People familiar with Linux will understand the term “jailed”, which in general terms mean restricting access and operations to a specific area within the target device.

The hacker community coined the term “jailbreaking” after successfully breaking out of this restricted environment allowing pirated apps to be installed on the phone and unlocking it to be used with other carriers.

The Firmware:

Apple provides firmware updates on a periodic basis which update the operating system, radio baseband and other device firmware. Although these updates have not resulted in loss of user data, it is not recommended that the firmware be upgraded during the forensics process.

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Mobile Forensics

With the explosion of mobile devices there is little doubt that the number of security incidents were a mobile device is involved will also increase exponentially.

My next couple of posts will look at what is takes to perform forensics on mobile devices targeting specifically the iPhone, the Blackberry and the Android platforms.

Some interesting statistics on the iPhone in particular and the number of them that AT&T activated in the last couple of years. As can be seen below the number of iPhones activated in the 3rd quarter 2009 was 3.2 millions devices in the US alone.

This doesn’t equate to iPhone’s sold because activations would also count dad’s giving their iPhone to their daughter and buying a new one for themselves, which would mean 2 activations but just one iPhone bought.

According to AT&T they added 2 million subscribers to that quarter. Nevertheless the evidence is there on an upward trend.

The graph below shows the how activations for the 1st quarter of 2010 rose by 50% over the previous quarter.

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Accurate Risk Assessments

As professionals in security we are constantly researching new technologies to keep our skills sharp. The Internet Storm Center was formed to assist with keeping our peers aware of the fast paced changes in vulnerabilities, patches, hacks, worms, Trojans and threats in general.

How we communicate these risks to our key decision makers sometimes can be a challenge. A recent example would be the Conficker April 1st situation. It was important for us to convey the sense of urgency we felt to have MS08-067 patched, as well as cross checking all our systems for updates being rejected, anti-virus definitions up-to-date and so on. My question to you is “did you communicate the risk effectively”? Were you able to give a complete and accurate risk assessment to your management?

Remember that risk assessment is the process of identifying a threat, understanding how that threat relates (vulnerability) to your organization, assessing the cost and providing that information to management. The formula is simple, let’s break it down.

Risk = Threat x Vulnerability x Cost

  1. State the threat in language that is easily understood. It is your job to decrypt the threat for your management team.
  2. Portray clearly and accurately what the threat could do and how it would possibly perform in your environment.
  3. Identify the number of assets which may be affected by the threat. What is percentage of vulnerable devices in relation to the total devices? (Servers, workstations, operating systems, Internet exposure)
  4. Identify the corrective measures which are available to be taken.
  5. Calculate the SLE (Single Loss Expectancy). What is the dollar value of the cost that equals the total cost of the risk?
  6. State how the remediation would lower the exposure to the organization and give a cost for those actions.
  7. Recalculate the SLE with projected remediation included.
  8. Provide status of the protection mechanisms already in place (anti-virus definitions, IPS signature detections, patching statistics).
  9. Then allow management to make an educated decision based on risk to the enterprise, not just the security event itself.

By utilizing this concrete methodology, we can lessen the influence of media hype and provide a professional cost based opinion to those best equipped to make enterprise decisions.

Source:  http://www.dshield.org/diary.html?storyid=6223 by Mari Nichols

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Conficker Gets Ready To Strike

Without a doubt the whole security professional community have their eyes on the Conficker.C variant which is designed to do something on April 1st.

So what is that something? We’ll find out within 24 hours.

What we do know is that this variant of Conficker has become better at preventing removal and others from taking control of the network of worm infected computers.

The Conficker worm will begin to poll 500 different domain names every day looking for updates to download doubling its current rate.

Interestingly enough one of my most popular posts is on the removal of the Conficker worm from a network environment here and over the last couple of days visitors have exploded exponentially.

In my two other posts in which I talk about the Microsoft flaw and the Social Engineering components of the worm, I take a rather passive approach to the problem which is based on having contingency plans to prevent, contain and remove the worm from infected computers.

A more pro-active approach would be to look for infected machines without waiting for the symptons to appear by actively scanning the network for computers which have been infected.

Locating computers which have been infected with Conficker using a network scan has kept me up multiple nights, until the guys at Honeynet.org came up with the tool here. Thanks to DShield.org for linking to it in their article on locating Conficker.



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