Secure Digital (SD) cards and USB flash drives are both portable storage devices commonly used to store and transfer data between devices. SD cards were initially designed for use in cameras but are now found in many consumer electronics. USB drives rose in popularity due to their small size and plug-and-play functionality across devices with a USB port. Both provide a compact way to store and move files, photos, videos, and other data.
SD cards come in a range of storage capacities, from a few gigabytes up to one terabyte for high capacity SDXC cards. They consist of flash memory and a controller in a small plastic shell, nearly the size of a postage stamp. USB flash drives also contain flash memory chips and a controller encased in plastic housing, but are designed with a USB connector to easily plug into computers, phones, and other devices. While their specific capabilities vary across manufacturers and models, SD cards and USB drives both enable users to expand storage and transfer files through a portable, removable format.
Physical Security
SD cards are small and can easily get lost or stolen if not properly secured in a device or case. Their diminutive size makes them easy to misplace and hard to find if dropped. In contrast, USB flash drives are larger and easier to keep track of (Source). However, the small form factor of SD cards allows them to be concealed in a wallet or hidden location as a backup. Ultimately, SD cards require more care and diligence to keep physically secure compared to standard USB flash drives.
Encryption
Both SD cards and USB drives have the capability to be encrypted, but this encryption is not always enabled by default 1. To enable encryption, users must actively turn on encryption features through device settings or third-party software. The level of encryption offered can vary between device brands and models. For example, some USB drive manufacturers like Kingston and SanDisk offer encrypted USBs that leverage AES 128-bit or 256-bit encryption. Similarly, some SD card brands like Samsung EVO Select have built-in AES 256-bit encryption. But without explicitly enabling encryption, both USB drives and SD cards will store data in a plain, unencrypted format by default. So while both devices offer encryption capabilities, it is up to the user to take advantage of these features.
Malware Risk
Both SD cards and USB drives carry the risk of spreading malware if proper precautions are not taken. Malware can spread to removable media in several ways – if an infected computer writes malicious files onto the drive, if the drive is inserted into an infected computer, or if the drive itself contains pre-installed malware. According to CISA, malware has often been found on free USB drives distributed at events or conferences (1).
To reduce the malware risk, experts recommend scanning removable media with up-to-date antivirus software before first use and after inserting into any unknown device. Files should not be opened directly from removable drives without scanning first. Care should also be taken to only obtain drives from trusted sources (2). While malware risks are similar between SD cards and USB drives, USB drives tend to change hands more often and connect with more systems, potentially increasing exposure.
Sources:
(1) https://www.cisa.gov/sites/default/files/publications/RisksOfPortableDevices.pdf
(2) https://www.cisa.gov/news-events/news/using-caution-usb-drives
File Recovery
When it comes to file recovery, both SD cards and USB flash drives make it possible to recover deleted files, although the success rate depends on whether the storage has been overwritten. Once a file is deleted, it is not completely erased from the storage device right away. Instead, the link to that file’s data on the storage media is removed. As long as the data itself has not been overwritten by new files, data recovery software can scan the device and rebuild the file structures to restore deleted files [1].
However, if new data has been written over the deleted files, it becomes much more difficult to recover them. The more a storage device is used after deletion occurs, the higher the chance of overwriting and permanent data loss. Both SD cards and USB flash drives face this limitation. To maximize chances of recovery, it’s best to stop using the device immediately after accidentally deleting files or formatting and turn to professional data recovery services. Overall, while file recovery is often possible, it largely depends on the overwrite status and quick action by the user. Both SD cards and USB drives share this data recovery characteristic.
Hardware Vulnerabilities
Hardware such as USB drives and SD cards from untrusted sources could contain embedded firmware or hardware vulnerabilities that are exploited once connected to a computer. For example, fake or altered USB devices can be designed to emulate keyboard keystrokes to run malicious commands, known as a “USB Rubber Ducky” attack (CSO Online, 2022). Some risks of using removable USB/SD devices are:
- Malicious firmware can bypass security controls and directly attack the system’s memory and resources (CISA, 2012).
- Devices may be altered to act as a listening device or packet sniffing tool to intercept sensitive data (CISA, 2012).
- Unknown USB/SD devices could contain hidden storage partitions that deploy malware onto the host computer automatically.
Overall, malicious USB/SD hardware poses a significant vulnerability. Users should only use devices from trusted sources to limit exposure to embedded firmware or hardware hacks that can compromise security.
Cloud Backup
Both SD cards and USB drives can be used to store backup files that can later be uploaded to cloud storage. According to Quora, cloud storage has the advantage of 24/7 availability as long as you have an internet connection. USB drives are limited by their storage capacity.
However, Tom’s Guide notes that external drives like USB and SD cards allow you to store data offline and avoid monthly storage fees associated with cloud storage. Both options can work together, using the external drive for offline backup and cloud for online backup.
Cost
SD cards used to be considerably more expensive than USB flash drives, especially for higher capacities. However, prices have come down dramatically in recent years and now there is little difference in cost between USB and SD cards for a given storage amount.
According to this Reddit discussion, USB drives are now often cheaper than comparably sized SD cards. For example, a 64GB USB drive may cost around $10 whereas a 64GB SD card is typically $15-20.
One advantage SD cards still have is that micro SD cards with adapters are very cheap per GB. But regular sized SD cards are now generally more expensive than standard USB flash drives for a given capacity.
Speed
When comparing the speeds of SD cards and USB drives, USB 3.0 is generally faster than most SD cards. According to Flash Drive vs SD card: Which is better? – USB Memory Direct, USB 3.0 has a maximum transfer speed of 5Gbps. In comparison, even high-speed SD cards usually max out below 100MB/s or 800Mbps. However, newer versions of USB like USB 3.1 (10Gbps) and USB 3.2 (20Gbps) are even faster.
As noted in the Quora discussion USB vs MicroSD – Which is faster and more reliable?, USB 3.0 can be nearly twice as fast as the fastest SD cards available today. So for transferring large files like videos, USB 3.0 will generally be the faster option. However, for small file sizes, the difference is less noticeable.
Conclusion
In summary, both SD cards and USB drives have their pros and cons when it comes to security. On the one hand, SD cards are more difficult to physically lose or have stolen due to their small size. The data on SD cards is also encrypted by default, adding a layer of security. However, SD cards can be more vulnerable to data corruption and physical damage than USB drives.
USB drives have the advantage of often having more storage space, faster transfer speeds, and being less prone to data corruption. However, they are physically larger and easier to misplace or have stolen. USB drives also do not automatically encrypt data like SD cards. This means an extra step is required to encrypt and password-protect USB drive data.
In the end, both options come with risks if the proper precautions are not taken. The recommendation is to encrypt and password-protect any sensitive data that is stored on either device. Additionally, enabling automatic cloud backups provides an extra layer of protection against data loss. With strong passwords and encryption enabled, both SD cards and USB drives can be relatively secure options for portable data storage. Just be mindful of physical security, avoidance of malware, and proper file management.