The first text message was sent in 1994, at a time when phones did not have keyboards and the sender had to type the message on an actual computer. Over the last twenty-three years, text messaging – texting, lol – has quickly become one of the most popular forms of communication. Whether for work or for personal communication, texting is easy, accessible, fast and efficient. Most people feel a wave of anxiety any time they mistakenly forget their phone at home, or even worse, their phone gets stolen or lost. This isn’t surprising: our phones house the data of our daily lives – Internet browsing, photographs, applications, social media, email, and, of course, text messages.
Technology has advanced by leaps and bounds since 1994, and as a digital forensics company specializing in mobile phone forensics we are often asked to look at a client’s mobile device (smartphone, tablet, or other smart accessory) even before data from a subject PC is brought into question. As cellphone companies offer new devices to consumers at least annually, and operating system updates almost weekly, digital forensic tools must constantly adapt and advance alongside these changes.
Here are answers to the top four questions we get asked when addressing forensic analysis of cellphone data (a quick caveat: these are generalized answers; device make, model, capacity, usage, and condition will greatly affect text message findings):
#1: Where are cellphone text messages stored? Text messages are stored in a database maintained on the device, which is designed to track whether a message has been delivered, read or deleted. This database also stores information about the message attachments, such as pictures, video and audio. Our forensic tools are designed to extract these messages into a standard format for processing, searching and review.
#2: How far back will text message chains go? This is a difficult question to answer and depends on the size of the device storage and how full it is. Since each mobile device we encounter offers varying degrees of storage space there is no set timeframe that is maintained. The usage patterns of the user will also come into play, since the frequency by which a user sends text messages can potentially shorten the lifecycle of existing text messages on the device when the need for storage space arises.
#3: Are deleted text messages recoverable? When a text message is deleted, the message itself will disappear from the text thread. However, the entry is marked in the cellphone database as “deleted” and while it is inaccessible to the average user, it can be recovered for a short period. Over time, as the user sends and deletes text messages, the space for deleted entries will be reused and the messages that were deleted in the past will eventually become overwritten. This process means that a message that was deleted six months ago could quickly become unrecoverable from the device’s database. Also, it should be noted that during this deletion process metadata, which captures details of the message that could include transmission date, to/from names and phone numbers along with other information may not remain intact. The sooner the device is forensically imaged, the better.
#4: How should text messages be produced? Text messages are tricky when it comes to producing them. There are a few complications with this medium that should be addressed as soon as the parties realize texts will be used as evidence. First, considering how far back a text message thread could go (potentially years), it is important to understand how large such a production could be. If you decide to search text messages for particular terms, do you want to include surrounding messages to provide context? How far back and how far forward? The format in which review tools look at text messages also can differ greatly. Is one lone document with thousands of pages addressing a single thread what is needed or just a single bubble? Capsicum can assist you in answering these questions and making your collection a successful one.
For these reasons and more, it is important to have a digital forensics expert image a cellphone as soon as possible in order to preserve text messages. People tend to be more casual about the contents of text messages, quickly composing and hitting “send” without a thought to their recoverability.