To accompany the fantastic research carried out by Matt Davies (SYTECH) et al. from:
The presentation slides from the DFRWS (Digital Forensics Research Conference) Europe 2015 Annual Conference are now available below:
To accompany the fantastic research carried out by Matt Davies (SYTECH) et al. from:
The presentation slides from the DFRWS (Digital Forensics Research Conference) Europe 2015 Annual Conference are now available below:
Matt, you’re a digital forensics analyst at SYTECH. Tell us a bit about your role and what it involves.
My role at SYTECH predominantly involves the extraction and analysis of embedded devices, such as mobile phones, tablets, satellite navigation systems, games consoles, unknown devices etc. The examinations I am involved in vary considerably and range from indecent images of children (IIOC) to providing assistance in murder investigations. Working for a private organisation, such as SYTECH, allows me to experience both prosecution and defence based cases.
What first made you interested in digital forensics as a field?
It was the varied nature of the work accompanied by the opportunity to make a difference that attracted me to the field of Digital Forensics.
I really didn’t want a mundane or repetitive job; I wanted a career that would provide both challenges and stimulation, so far I have not been disappointed! I have a real passion for forensics and love what I do.
At DFRWS you presented some research on forensic analysis of a Sony PS4. Could you briefly outline this for our readers?
The Sony PlayStation 4 is the most powerful 8th generation games console on the market. As of March 2015, there are over 20,000,000 devices in worldwide circulation. The console’s security features, such as encryption, face recognition technology and passcode protection, make this device the perfect weapon for criminals. Therefore it was essential that an analysis method be devised for this device. The proposed best practice methodology is the result of over 50 experiments conducted upon the PlayStation 4 over a 12 month period.
In the first instance the console’s hard drive is removed, imaged and restored upon a duplicate HDD using a Linux based system. A shadow drive is then inserted between the console and the duplicate drive, which receives all write requests and as such prevents the alteration of data stored upon the HDD. The operational effectiveness of the shadow drive was evaluated in the following manner: The duplicate HDD was imaged and verified. An online analysis of the console’s Internet web browser was conducted and the HDD removed and verified. A comparison of both the MD5 & SHA-1 hash values concluded that no alterations were made to the HDD during the analysis.
A technique that can be exploited by the user enables images viewed online to be stored upon the device. These images are stored as screen captures and can easily be copied to a USB pen drive for evidential purposes. Image and video content acquired via the console and saved to an alternative device (under a different file name) contain metadata that includes the device make & model, firmware version used, original file name and the date and time created. This information can be correlated to the suspected device responsible for creating the artefacts.
One of the greatest challenges with the PlayStation 4 is the continuous updating of system firmware. It has been observed that firmware updates take place at around 8 week intervals and provide additional features as well as “system stability” updates (suspected updating of encryption keys). For each firmware update where the experiments were repeated, the results differ considerably between firmware versions.
You mentioned that one investigative challenge is that Sony is now storing the majority of PlayStation data on the PlayStation Network rather than on each device. Talk us through the unique challenges associated with this, and how they might be addressed.
Having previously evaluated the operational effectiveness of the shadow drive when viewing non PlayStation Network (PSN) dependent content, a second experiment focusing upon PSN was conducted. The experiment involved connecting the console to PSN and sending a single message to a friend, whilst utilising the shadow drive. The console was then rebooted and the message content analysed. The first iteration demonstrated that the message was not visible upon rebooting the console. For validity reasons, the experiment was repeated. On this occasion both the initial and second messages were visible. The experiment was repeated a final time and it was apparent that all messages sent whilst connected via a shadow drive were visible. Therefore, the shadow drive does not prevent data stored in PSN being altered. This presents a significant challenge as data stored in the PSN is duplicated, in part, upon the console’s HDD, meaning that an investigator accessing PSN content without a shadow drive could potentially overwrite existing data or unintentionally delete vital evidence.
The best solution is to use a secondary console to view PSN content. Creating a basic user account without any data will result in that account being populated with the user’s content upon logging into PSN, including unique PSN gamer ID, profile information, messages, party, friends, What’s New, Notifications etc. In addition, an investigator can also access partial PSN data by logging into the suspect’s account via a PC browser. The Sony Entertainment Network (SEN) can be used to prove ownership and contains the user’s real name, address, credit card details etc.
Additional challenges are presented by the console’s remote access features: such options should be disabled, the console restarted and the changes verified prior to conducting an online analysis of the device. In addition, investigators should disable the PSN automatic login feature in order to prevent the alteration of PSN content.
How do you think the world of digital forensics will change over the next few years?
The industry trends seem to indicate a significant increase in the use of security features such as encryption, biometrics and passcode protection. Over the coming years such features are likely to become more widely utilised, and as a result present greater challenges to forensic investigators.
It has been said for many years that the line between personal computers and embedded systems is becoming increasingly blurred. The technological advancements, accompanied by larger storage capacities, will continue to present significant problems for digital investigators. According to Sony, the PlayStation 4 possesses 43 times the processing power of the PlayStation 2 and 10 times that of the PlayStation 3. One can’t help but wonder what the PlayStation 5 will have in store for us!
The sharing capabilities of the PlayStation 4 enable social media websites such as Facebook, Twitter and Youtube to be synced with the device. Tablets and mobile phones also encourage users to share content via social media applications, the whole area seems to be expanding at an alarming rate.
We only need look at the development in mobile phone forensics over the past 5 years to see how far the field of digital forensics has already come. The challenges faced by investigators in the coming years will greatly surpass those seen in previous years, providing a solution to these is far from impossible. Perhaps the greatest change to the field of digital forensics will be the operational requirement for dedicated Research & Development teams within every organisation. We might also see a significant shift from traditional forensic techniques and the reliance upon industry standard tools. There has been a great deal of debate in this area and as to whether or not the whole forensics process is becoming automated. I think it’s an interesting discussion and one that is likely to continue in the future.
I am currently continuing further research into game console forensics and intend on presenting the results at DFRWS 2016, Switzerland.
Matt Davies is a Digital Forensics Analyst at Sytech, who work on digital investigations across all areas including criminal justice, civil litigation and corporate.
Forensic Focus interviewed Matt at DFRWS, the annual Digital Forensics Research Workshop, which took place in Dublin from the 23rd-26th of March. The next workshops will be held in Philadelphia in August 2015, and Switzerland in March 2016. You can find out more and register here.
The primary function of a games console is that of an entertainment system. However the latest iteration of these consoles has added a number of new interactive features that may prove of value to the digital investigator. This paper highlights the value of these consoles, in particular Sony’s latest version of their PlayStation. This console provides a number of features including web browsing, downloading of material and chat functionality; all communication features that will be of interest to forensic investigators. In this paper we undertake an initial investigation of the PlayStation 4 games console. This paper identifies potential information sources of forensic value with the PlayStation 4 and provides a method for acquiring information in a forensically sound manner. In particular issues with the online and offline investigative process are also identified.
Gone are the days of games consoles being regarded as mere entertainment systems. Games console technologies are advancing at a far greater rate than that of game console forensics. This is evident from devices like the PlayStation 3, relatively little is known of this console in terms of forensic analysis, yet the PlayStation 4 has been released. It has been identified by several authors including, (Xynos et al., 2010), (Conrad et al., 2009), and (Turnbull, 2008) that the distinction between games consoles and personal computers is becoming increasingly blurred. Modern gaming consoles possess far greater functionality and processing speed, and connectivity features similar to standard PCs. Game console forensics will continue to become a specialist area, with its own bespoke challenges to the digital investigator.
Currently there are over 10 million Sony PlayStation 4 games consoles in worldwide circulation (Peckham, 2014). At present there is little information available offering forensic investigators an insight into what information of interest is stored on this device, or how to acquire data in a forensically sound fashion. This paper seeks to provide a greater insight into the PlayStation 4 in relation to a digital investigation, and to present a methodology that can provide guidance to investigators working with such a system.
The rest of this paper is arranged as follows. Section 2 highlights literature that has helped shape our investigation, Section 3 presents the forensic challenges an analyst may encounter, Section 4 describes the empirical experiment methodology we undertook to discover what data is of importance, Section 5describes the forensic analysis of the PlayStation 4, Section 6 presents our methodology for extracting useful information, Section 7 and Section 8 highlight conclusions and future considerations.
Games platforms present a number of challenges in terms of accessing and interpreting data, as each system is a proprietary platform with a unique operating system. While there has been work on the forensic analysis and acquisition of data from other game platforms, there has been little work to date on the Sony PlayStation 4. However we can learn of the types of challenges we are likely to face with such a device by reviewing recent work in similar embedded systems.
Previous work (Moore et al., 2014) has provided a preliminary analysis of an Xbox One, using initial exploratory methods such as file carving, keyword searches, network forensics and file system analysis. The greatest challenge faced by Moore et al. (2014) appears to be the encrypted and/or compressed nature of the files and game network traffic, thus making extraction and analysis somewhat difficult. However, an analysis of the NTFS filesystem did allow for file timestamps to be recovered, and some encrypted network traffic could be related back to which game was played.
The analysis conducted by Conrad et al. (2009) was of particular interest as we were presented with similar challenges to those posed by the Sony PlayStation 4. A series of experiments was conducted by Conrad et al. (2009) on the PlayStation 3 and established that, due to the console’s utilisation of AES encryption (Ridgewell, 2011); a native analysis method was required. The write blocker experiment conducted byConrad et al. (2009) concluded that it is not possible to prevent evidence being altered during the analysis of the Sony PlayStation 3. However the methodology produced by Conrad et al. (2009) remains valid, as the analysis undertaken by investigators is repeatable.
According to Ridgewell (2011) the PlayStation 3 adopts an AES 128 encryption format, exploitable through the various processes of retrieving the cryptographic keys used by Sony, identified by hacking group fail0verflow. They also utilised various network forensic techniques and software tools in order to evaluate the console’s security vulnerabilities, observing that the PlayStation 3 TCP & UDP communications are unencrypted.
The work undertaken by Xynos et al. (2010) expands upon the research of Vaughan, 2004 and Burke and Craiger, 2007 and Dementiev (2006), establishing that is possible to recover remnants of information relating to online gameplay from the consoles hard drive; such as time and date stamps and the online gamer ID’s of all players that had participated. As highlighted in Read et al. (2013) there is a need to keep up to date with the modding community, as some developments may have far reaching consequences, which could even include hiding entire partitions from forensics tools.
The greatest challenge presented to digital investigators in relation to the PlayStation 4 is the non-standard file system; unlike the Xbox One that at least allows NTFS metadata retrieval (Moore et al., 2014). The hard drive contained in the system appears encrypted and this presents a significant barrier. The hard drive can be imaged via a write blocker, however its encrypted nature means it would be difficult to provide an in depth analysis that includes operating system artifacts. For this reason the most useful route is via the user interface, as with other embedded and smart devices (Sutherland et al., 2014), whilst using appropriate write blocking technology to prevent changes to the data.
A further challenge is the user’s ability to alter the information stored within the PlayStation Network (PSN). A user accessing a PSN account via an alternative console, PS4 Companion APP (Sony, 2014a) or PlayStation Vita (Sony, 2014b) possesses the ability to modify or remove potential evidence.
As with many other eighth generation games consoles, the sharing of user-generated content via social media is prevalent on the PlayStation 4. The very nature of sharing hi-scores, game achievements and recorded videos with others requires the device to be connected to the Internet and use of Sony’s cloud services. From a forensic investigator’s perspective, this may mean the hard drive is not the most important data source as it has been in previous generations of games systems. It is possible that user generated content will not even appear on the hard drive at all; online investigations may be required to obtain evidence.
In the production of any guidance or methodology for information extraction, which may be relied upon in courtroom proceedings, standard best practice must be adhered to. In the UK the Association of Chief Police Officers (ACPO) Good Practice Guide for Digital Evidence version 5 (Association of Chief Police Officers (2012)) provides current best practice for evidence acquisition. All tests performed on the PlayStation 4 have been carried out with respect to ACPO guidance.
We performed an initial study of available literature and an empirical investigation of the PlayStation 4 to identify the areas that a digital forensic investigation may wish to examine. In particular, the Frequently Asked Questions (FAQ) posted by Shuman on the official PlayStation blog (Shuman, 2013) proved to be insightful when trying to identify which areas to analyse. The empirical investigation comprised of powering on the PlayStation 4, navigating through the various in-game menus and noting areas that may provide evidence of usage and/or communication during an investigation. We primarily concentrated on finding areas that may help identify the who, what, when and where aspects of an investigation. The “who” focused on identifying which user generated the evidence (The PlayStation 4 can hold up to 16 user profiles (Sony Computer Entertainment America and LLC, 2014)), “what” content can be created with the new features of the device, timestamp information to indicate “when” the information was generated, “where” the information could be stored (hard drive, external media, Internet/cloud). After exhausting the features on the device, a number of areas were revealed that could help answer these questions. The features found to be of interest are detailed in Table 1.
|PlayStation Network (PSN)||The vast majority of features available to Sony PlayStation 4 users are reliant upon a PSN membership.|
|Sony Entertainment Network (SEN)||Viewing SEN content through a PC web browser, will reveal the user’s real name, address, credit or debit card information, transaction history, linked devices and sub account information.|
|Internet Browser||The Internet browser does not support PDF or office documents. Thumbnails are stored in the browser history provide an indication of user’s most recent activity. Google search terms, Google map searches, 100 web pages visited, 100 Bookmarks (Sony Entertainment Inc, 2014) and 8 most recently visited webpages are available.|
|ShareFactory||The ShareFactory enables players to share, via USB/social media, content recorded via the PlayStation camera or recent game footage. In addition, users possess the ability to edit footage and to record voiceovers or video commentary.|
|System Storage Management||Provides system storage information such as D disk usage, application saved data, video & screen captures and available disk space.|
|Error History||A log of various errors encountered by the system, including time/date values, error codes and the nature of the error.|
|What’s New||Recent user activity and those on their friends list including recent gameplay, recent achievements and new additions to their friends list.|
|Trophies||Relate to specific gaming titles and provide time/date values of when achievements were awarded.|
|Profile||Personal data/unique user handles and other content generated by a user.|
|Friends||A user’s friends in their Friends list can be linked to Facebook. Is it possible to find communications between the user of the system and others. Real name requests can be sent, meaning that a user’s real name will be displayed in all communications. Up to 2000 friends.|
|Party Messages||The Party feature allows up to 8 users to enter a group conversation.|
|Messages||Messages between individuals and multiple users.|
An experimental methodology was devised by empirically exploring the areas identified in Table 1 and noting locations that may be of interest to an investigator, an overview of the process we undertook is presented in Fig. 1. The methodology was created to assess if it was possible to retrieve data from each location. This involved deliberately introducing data into those different areas and observing if it could be retrieved later. During the course of the experiment, firmware updates became available for the PlayStation 4. Each revision was noted, installed, and the experiment methodology was run again to assess if there were any negative impacts to the evidence acquisition process described in Section 6. The following selection of firmware was used: 1.01, 1.50, 1.51, 1.52, 1.60, 1.61, 1.62, 1.70, 1.72, 1.75 and 1.76 (the latest at the time of writing). Unfortunately we were unable to test all revisions, as the console would only allow us to update to the latest, skipping incremental versions.
The experiment was carried out (for each firmware version) as follows.
Activate video capture device, record time.
Ensure that all of our actions on the system are recorded for future reference.
Activate PlayStation 4. Record time as set on console. Observe any offset between real time and time on console. Offset must be applied to any data retrieved to ensure correct time is recorded.
Introduce sample dataset, record time and data introduced. The sample data (detailed in Section 4.3) is designed to deliberately cause the console to store information in relevant areas from Table 1. Through meticulous recording, we can later identify if our actions are retrievable from the PlayStation 4.
Turn off PlayStation 4. Deactivate video capture device, record time. The video capture provides evidence of our introduced changes to the system during this iteration of the experiment.
Forensically image PlayStation 4 hard drive. Though the files are inaccessible, we keep an image of the hard drive as best evidence such that if our empirical investigation alters evidential data, we can restore the hard drive from the image file and reassess. We used FTK Imager v.3.1.5 to create the forensic images, and the EnCase E01 format to compress files, as the uncompressed RAW images are large.
Turn on PlayStation 4; investigate areas in Table 1 to identify user actions introduced during this experiment iteration.
Compare the data retrieved in relation to the data introduced. Note information, timestamps and any other items indicating use of the PlayStation 4.
After a new firmware update was applied, the hard drive was forensically wiped and then reinitialised in the PlayStation 4 to ensure any recovered data was from the current iteration of the experiment and not from a prior run. The purpose of running the experiment after a change in firmware is to determine if these changes will help or impede our ability to obtain data.
The PlayStation 4 can store information on the local hard drive and online. Different accounts had to be created in order to assess the features in Table 1. Local (offline) user accounts comprised of three users, User1, User2 and User3. Two further online accounts, the free PSN (PlayStation Network) account and the subscription-based PlayStation Plus account was also created to ensure all features would be available. The PlayStation Plus account was used to download a free title, “War Thunder”, and participate in online gameplay to check for usage later.
To assess the messages functions, contacts were added to the Friends List and both individual and group messages were sent to selected users. A Facebook account was created to enable both the social media aspect of The ShareFactory and the Share button feature on the DualShock 4 controller. A number of other Facebook users were linked to this account to determine if they appeared elsewhere on the console.
The Trophies feature worked with both offline and online game play. Two software titles available to us, “Call of Duty: Ghosts” and “Need For Speed Most Wanted” were used in both modes to assess if usage patterns could be determined by in-game trophy awards.
To assess the Error History, we observed that interacting with Internet dependent features offline would result in error messages being added to the log. We would remove the Internet connection, note the time and the function accessed, and then determine if the information was generated. This knowledge allowed us to deliberately create known system errors to assess the Error History feature.
The Internet browser is known to store 100 visited websites in its history and bookmarks, and 8 most recently used webpages. To assess this, we accessed 103 websites and stored 103 bookmarks, consisting of direct links to images, web pages, websites and duplicate entries.
A number of features allow the user to store data to a FAT32 formatted USB memory stick. We stored ShareFactory projects and pictures obtained from the Internet web browser to a flash drive for later analysis.
As presented in Fig. 1, a number of different tests were conducted to assess the ability of a forensic investigator to identify usage of a PlayStation 4. The test data in Section 4.3 was introduced to successive firmware updates (see Section 4.2), and any notable changes between revisions are discussed below.
An initial triage of a PlayStation 4 hard disk, using FTK Imager v188.8.131.52, revealed that the disk structure consists of an unknown filesystem split into 15 partitions as can be seen in Fig. 2. Our analysis of the PlayStation 4 will concentrate on using the native user interface to locate information.
We employed the data carving utility of AccessData’s Forensic ToolKit (FTK) v3.2 in an attempt to retrieve additional files from a forensic image taken of the PlayStation 4. FTK v3.2 was unable to detect the presence of any files. This strongly suggests either encryption or a bespoke container format.
Several experiments were conducted upon the PlayStation 4 Internet web browser. The first of which aimed to determine whether the browser stores only unique websites visited, as seen in the PlayStation 3 (Conrad et al., 2009). The experiment involved visiting 103 websites and selecting various web links. It was noted during the experiment that in addition to all web links selected, Google search terms also appear in the PlayStation 4 web browser history. Furthermore, an analysis of the web browser history, bookmarks and most frequently used pages concluded that the time & date upon which events occurred, is not obtainable via the native interface.
Further experiments involved utilising the Internet web browser to store pictures upon the console’s hard drive. It was established that there are only two means by which to successfully complete this task. The first is by storing web images as bookmarks, the second is to store screenshots captured via the share button on the DualShock 4 controller.
We conducted a system wide analysis of the Sony PlayStation 4, focussing upon the retrieval of date and time stamp information. It was discovered that the majority of features, such as Trophies, What’s New etc., provided such information. In contrast, applications such as the Internet web browser did not present any form of date and time information, whilst the Party and Messages features presented only the dates upon which messages were sent and received.
After performing an analysis of the PlayStation 4 via the user interface, we tried restoring the hard drive back to the acquired image taken before turning on the console. The purpose of this was to determine if the system would accept a previously stored system, which a forensic examiner could use to verify their findings. We converted our image to RAW before transferring onto the drive with the UNIX tool dd. FTK Imager (v3.1.5) was used to verify the restored drive that confirmed it was identical to the image file. The console booted the restored version without any issues.
Inspired by Conrad et al. (2009) we used a Tableau T35is write blocker as a man-in-the-middle given it has SATA ingress and egress connections (Fig. 3). We kept the system offline to examine what could be obtained from the hard drive alone. Unlike Conrad’s experiment on the PlayStation 3, we were able to successfully boot the PlayStation 4 and view data via the in-game menus. However, any functions attempting to write to the hard drive (such as System Storage Management calculating storage space) caused the system to become unstable and stop responding. A hard reset was required to boot the system again.
An offline analysis of the PlayStation 4 utilising the T35is concluded that it is possible to retrieve the key information outlined in Table 1 with the exception of the ShareFactory, System Storage Management and What’s New. It was noted during the analysis that any interaction with some PSN dependent features would result in the generation of system errors due to the system being offline. The T35is prevented the errors from being written to the log and the system became unstable.
These results were obtainable for all firmware revisions up to and including 1.62. After we conducted the experiment during the firmware 1.70 iteration, we found that all the PSN areas of the console were now inaccessible offline, and required logging into the PSN network.
During the firmware 1.72 iteration experiment, it was only possible to recover data relating to the Internet web browser and system setting information.
Furthermore on firmware 1.75 the system would boot successfully with the write blocker but any attempt made to open the Applications pane would result in system instability. From 1.75 onwards we had to use a Voom Shadow 3 (see Section 5.8 below) to let the PlayStation 4 write changes to a buffer whilst maintaining forensic integrity of the original drive.
This experiment compliments that in Section 5.6; by using a T35is write blocker (up to firmware 1.72) or a Voom Shadow 3 (firmware 1.72 and later) and enabling the Internet connection to allow access to online content, whilst disabling the ability to make changes to the local hard drive. We felt it was necessary to assess whether such a method would also prevent the modification of PSN dependent content. The experiment consisted of sending multiple messages to a specific user, whilst utilising the write blocker as a pass-through.
Upon restarting the console it was noted that the message sent was not visible. In order to validate the results the experiment was repeated. The second iteration revealed that the content of both messages were now visible. The results indicate that, investigators must be wary of messages previously sent via the PSN can be cached locally and remotely potentially leading to differences between an online and offline investigation.
The changes implemented in firmware version 1.75 prevented us from conducting an analysis of the Sony PlayStation 4 whilst utilizing the Tableau T35is write blocker. Accessing any of the menus in the same fashion as on earlier firmware resulted in system instability. As such a suitable alternative method of maintaining evidential integrity was sought.
The Voom Shadow 3 (Fig. 4) was identified as a potential alternative. In order to assess the device’s suitability, we connected the Voom Shadow 3 as a bridge between the PlayStation 4 and its hard drive. The console successfully booted and we were able to fully navigate the system without the stability issues experienced with the Tableau.
An offline analysis of the Sony PlayStation 4 ensued, focussing upon the recovery of data relating to the key features identified in Table 1. It was established that, in contrast to the analysis conducted upon Firmware version 1.72 with the Tableau (see Section 5.6), data associated with the features below were now obtainable offline with the Voom Shadow 3:
Internet web browser
System Storage Management
System time & date
Basic profile information
We used the Voom Shadow 3 to conduct an online analysis of the PlayStation 4 Internet web browser. The console was provided a LAN Internet connection and powered on. We selected the user and proceeded to sign out of the PlayStation Network (PSN). The console’s web browser was then launched; nine selections were made from the web browser history and the respective websites visited. The browser history was documented and the console restarted. The history, bookmarks and most frequently used pages were consulted and revealed that the alterations made during the analysis had not been stored.
The PlayStation 4 hard drive was removed and imaged using FTK Imager v3.1.1. It was reconnected and the online Internet web browser analysis performed. We then removed the drive and verified its integrity. Both the generated MD5 & SHA1 hash values were a match.
A local account used throughout the experiments was selected, and the passcode was set equal to ‘0000’ in Settings/Users/Login Settings/Passcode Management. The console was rebooted ensuring the Voom Shadow 3 was in write protect mode. We were subsequently prompted to enter the login passcode. We selected options/forgotten passcode and were then prompted to login to PSN. We then selected a new passcode, 9999 and access to the system was granted. The console was rebooted, prompting the login passcode. We entered 0000 and access to the system was granted. This allows an investigator to unlock a PlayStation 4 to look at local content without making changes to the system.
Up to firmware version 1.70 the PSN dependent content, such as Profile and Trophies could be accessed while the console was offline. From 1.70 onwards we had to connect the console to the Internet to access such information. This could be conducted with specialist hardware like the Voom Shadow 3 drive used in earlier experiments, but we explored the possibility of using the login data on a separate PlayStation 4 unit. Starting with a forensically zeroed hard drive on an identical specification PlayStation 4, a local account User1 was created and the menus were navigated to ensure the absence of data. We connected the system to the Internet and logged into the PSN with our account credentials. The following information was now available, even though this system had not been used to generate any content:
Various file formats were copied from a desktop workstation onto a FAT32 formatted flash drive. The files were stored in a folder labelled PS4 and consisted of 4 jpeg, 1 png, 2 pdf and a variety of Microsoft Office formats. The USB flash drive was then inserted into the PlayStation 4 and several attempts were made to upload the files. We found it was not possible to upload such files onto the PlayStation 4.
We investigated what type of content a user may download onto a memory stick. The ShareFactory was used to create videos of gameplay and the Internet web browser was used to perform Google searches for pictures of vehicles. Each picture was enlarged to full screen, by pressing square on the DualShock 4 controller, and a screen capture acquired. We used the Capture Gallery to publish duplicates of the content to the USB flash drive.
Using an Exif viewer allowed us to view the metadata from the fullscreen captures (Fig. 5). The image description field relates directly to the file name present upon the Sony PlayStation 4. The file name is provided by default and users are unable to make alterations to it from the console. In addition, the metadata also presents the firmware version installed upon the console when the image was acquired. Furthermore, we see that the PlayStation 4 is also identified as the camera model.
An analysis of the USB storage device was then conducted using the hex viewer in FTK Imager. It was observed that the MP4 generated via the ShareFactory contain the Application code (CUSA 0057) and the file name, which is the date and time upon which the file was created on the PlayStation 4 (Fig. 6).
To obtain the information described in Table 1 a forensic investigator should carry out the following steps:
Remove and forensically image the PlayStation 4 hard drive. Disable Internet connectivity. As discussed in Section 5.5, the image could be used to restore from at a later date to verify results.
Reconnect hard drive with a SATA write blocker that has a buffer feature (in Section 5.8 we described usage of a VOOM Shadow 3) as a man-in-the-middle between drive and console.
Activate video capture device, record time. Switch on PlayStation 4 and synchronize the DualShock controller.
Record time and date as presented on PlayStation 4 and take note of any difference with actual time. This offset will need to be applied to any timestamps (see Section 5.4) retrieved from the system.
Navigate to and record the data presented in the various functions as follows:
Error History – The Error History should be viewed first as errors may be introduced by the analyst during the investigation.
Internet Web Browser – Record history, bookmarks, and most recently opened.
System Storage Management
Capture Gallery – A USB drive may be used to download all content from the Capture Gallery (screenshots and videos, see Section 5.15).
Basic Profile Information
Error History – Record the errors generated during the course of the investigation.
Power off PlayStation 4, video capture device, record time.
If the PSN network login credentials are available, further information as detailed in 5.13 may be obtained on another PlayStation 4 console. If unavailable, a decision will need to be made by the investigator whether to take the original system online. Even with a write blocker, the danger using the original system is that cached content may be pushed online and update/overwrite existing information.
The proposed best practice methodology would allow digital investigators to perform an analysis of a write protected Sony PlayStation 4. The alteration of data is prevented and thus evidential integrity is maintained.
The amount of information retrievable however is directly dependent upon the firmware version installed on the console. Table 2 demonstrates that, during an offline analysis, it is possible to recover all user profile information from a console with up to firmware version 1.62 with a standard write blocker. Version 1.70 had limitations when viewing PSN content offline whilst 1.75 required the use of an advanced write blocker to view anything of substance. Similarly, Table 3 identifies what is retrievable during an online investigation for comparison.
|System Storage Management||✗||✗||✓|
P = Partially Retrievable.
|System Storage Management||✗||✗||✓|
As the Sony PlayStation 4 will not readily allow users to downgrade firmware, it is not possible to restore to previous revisions that allow greater offline access. As such, investigators will continue to be challenged by future firmware updates.
Further challenges are faced by the growing array of content only available online. Although evidence of usage is available on the console, many of the artifacts are only available when the PSN network is connected. Investigators may inadvertently alter data stored online by not disabling the network connectivity, and malicious users may use other devices to deliberately alter or remove incriminating content.
There are a growing number of accessories and interactivity options for the PlayStation 4 that may require investigation in their own right. The PlayStation camera enables users to utilize enhanced security features such as facial recognition to login. This could be used to secure the console, but could also be used to prove account ownership on a multi-user system if an individual was able to unlock a specific account. Future research should consider the implications of the PlayStation 4 connection capabilities with the Sony Vita and the PlayStation Companion App on smartphones and tablets. Any evidence of ownership data transfer and communications will be of interest to investigators.
Forensic analysis of a Sony PlayStation 4 – A first look – PDF Download
Mobile phones and other digital devices may be concealing a wealth of intelligence that could alter the course of an investigation but often remain hidden according to Simon Lang, Digital Forensics Manager at SYTECH.