Digital Device Seizure Protocols

Summary

Article Overview: Digital device seizure requires establishing clear legal authority, such as obtaining a specific warrant, and carefully documenting the chain of custody. Forensic examiners should promptly isolate wireless devices, use write blockers when imaging, collect volatile data first, and be prepared to address encryption and potential booby traps.

Digital Device Seizure Protocols: Forensic Best Practices for Legal Professionals

In today's digital world, electronic devices like computers, smartphones, and tablets often contain a trove of critical evidence in legal cases. From intellectual property theft to employee misconduct to divorce proceedings, the data stored on digital devices can make or break a case. However, improperly seizing and handling digital evidence can render it inadmissible in court or vulnerable to attack by opposing counsel. It is crucial that legal professionals understand and adhere to forensic best practices when it comes to digital device seizure. This article explores key protocols and procedures to follow to ensure digital evidence is properly and legally obtained.

1. Establish Legal Authority

Before seizing any digital devices, it is essential to establish clear legal authority to do so. In most cases, this requires obtaining a valid warrant based on probable cause, especially if the devices are owned by the suspect or defendant. There are exceptions for employer-owned devices or exigent circumstances, but in general, a warrant is the safest way to ensure the evidence will be admissible.

Consult with the forensics team to determine exactly what devices and data need to be covered in the warrant. Be as specific as possible. A warrant that is overly broad or lacking in particularity may be challenged and struck down, jeopardizing the evidence. Work with the judge to establish clear limits and protections.

2. Document Device Chain of Custody

Maintaining a clear chain of custody for seized digital devices is critical. As soon as devices are taken into custody, document the make, model, serial number, and condition of each device, along with the exact time and location they were seized. If possible, photograph the devices in place before seizure.

Each transfer of custody should be logged, with the receiving party signing and dating the log. Devices should be securely stored in a locked evidence room with restricted access. At no point should seized devices be left unattended or accessed by unauthorized parties. The goal is an unimpeachable record of every step in the journey from seizure to forensic analysis.

3. Isolate Wireless Devices

Many modern devices have wireless networking capabilities, including WiFi, Bluetooth, and cellular data. It is crucial to isolate seized devices from all networks as quickly as possible to prevent remote wiping or alteration of evidence. First responders should activate airplane mode, turn devices off, or place them in radio frequency shielding bags immediately after seizure.

More sophisticated suspects may use a "dead man's switch" that wipes a device if it does not connect to a network within a certain timeframe. Consult with the forensics team to determine whether a seized device needs to be periodically powered on and connected to a secure, monitored network to prevent activation of any anti-forensic measures.

4. Use Write Blockers When Imaging

Forensic examiners should never work with data on the original seized device. Instead, they should always create a forensic image, which is an exact bit-for-bit copy of the original storage media. Hooking up the device to create the image, however, risks altering the original data. Even just mounting a hard drive in read-only mode can still change file access timestamps.

The solution is to use write blockers when imaging devices. Write blockers allow reading data from the device without making any changes to the original media. Hardware write blockers sit between the device and the examiner's computer, while software write blockers work at the operating system level. Both are effective, but hardware blockers provide a physical guarantee that writes are blocked.

5. Collect Volatile Data First

When a device is powered on, it may contain volatile data stored in memory that will be lost when the device is turned off or loses power. Volatile data can include encryption keys, network connections, running processes, and temporarily cached files. In some cases, this volatile data can be more valuable than data stored on the hard drive.

If a seized device is found in a powered-on state, forensic examiners should attempt to capture a memory image and other volatile data before powering down. Tools like Faraday bags can safely isolate wireless devices while still allowing them to be powered on for memory acquisition. Once volatile data has been collected, the device can be safely shut down.

6. Be Aware of Potential Booby Traps

Technically savvy suspects may attempt to booby trap devices with destructive malware designed to trigger when the device is analyzed. For example, a "logic bomb" may be set to wipe a hard drive if a certain file is opened, or a network defender may activate a remote wipe if they detect law enforcement accessing a machine.

To guard against booby traps, forensic examiners should always work on an isolated network, preferably air gapped, when conducting analysis. Disk images should be mounted as read-only and scanned for malware before opening any files. Any scripts or executables should be treated as potentially malicious. If a malware infection is suspected, consider running the device's storage media through a hardware write blocker.

7. Address Encryption Promptly

Encryption is becoming more and more common, with many devices offering full-disk encryption built-in. Forensic examiners need to prioritize capturing unencrypted data, such as mounted encrypted volumes, while the device is still on. Encryption passphrases or keys should be obtained during seizure if possible, as this will save significant time during analysis.

If a device is encrypted, attempt to obtain the decryption key through consent, a warrant, or extracting it from the suspect's memory while the device is running. If the key is not available, assess the encryption software used and determine if there are any known flaws or vulnerabilities that could allow bypassing the encryption. As a last resort, brute force attacks can be attempted, but for modern encryption systems this is often infeasible.

8. Prepare for Analysis Onsite

In some cases, it may be necessary to perform preliminary analysis onsite during seizure to identify specific devices or data for collection. An employee's workstation might need to be triaged to determine if it was used for data exfiltration, or a suspect's phone might be previewed to confirm it was used in a crime. Quick look or triage analysis requires careful preparation and coordination.

Consult with the forensics team to develop an onsite analysis plan tailored to the specifics of the case and the type of devices expected to be encountered. A mobile device triage kit will include cables and adapters for various phones and tablets, software to bypass passcodes, and battery packs to prevent devices dying mid-analysis. Use a USB write blocker to safely boot up computers to triage hard drives.

9. Collect Data From Cloud Accounts

Increasingly, valuable data resides not on physical devices but in associated cloud storage accounts and backups. Suspects may have data stored in Apple iCloud, Google Account backups, Dropbox, or Microsoft OneDrive. Forensic examiners need to collect this data as well, but it can require additional warrants.

Consult providers' law enforcement guidelines for details on what account data is retained and how to serve warrants and preservation orders. Use caution when accessing cloud data from a seized device, as this can sometimes sync deletions and changes to the cloud account. It's safer to work with the provider directly to obtain a separate forensic export of the account data.

10. Validate and Document Evidence

The final step before analysis is to validate all the collected data to ensure its integrity. Examiners should check that file timestamps, metadata, and content match across the original media, forensic images, and examination copies. Calculate cryptographic hashes of the seized media and disk images to establish that the evidence has not been altered.

Prepare a forensic acquisition report detailing all the steps followed during seizure, imaging, and data collection. Document any issues encountered as well as the specs of all devices and tools used. Have this report peer reviewed by another examiner to confirm all procedures were followed properly. Be prepared to testify to the contents of the report when the evidence is introduced in court.

By carefully following these protocols and best practices around digital device seizure, legal professionals can ensure that digital evidence is collected and preserved in a forensically sound manner. Cutting corners or failing to implement proper protections can not only jeopardize the admissibility of key evidence, but can sometimes result in sanctions for evidence spoliation. By getting it right from the very beginning, legal teams can build the strongest possible case.

References

• Apple iCloud law enforcement guidelines (implied, not explicitly cited)
• Google Account backup law enforcement guidelines (implied, not explicitly cited)
• Dropbox law enforcement guidelines (implied, not explicitly cited)
• Microsoft OneDrive law enforcement guidelines (implied, not explicitly cited)

For more insights, read our Divorce Decoded blog.