Frequently when troubleshooting or cleaning PCs (ah, the joys of small business IT) it’s useful to have a bundle of tools that you can use. I generally use multiboot antivirus CDs created with Shardana Antivirus Rescue Disc Utility (SARDU) with additional utilities put in the Extras directory, but sometimes it’s hard to beat the convenience of a USB flash drive. Unfortunately very few flash drives still have the hardware write protect switch that was common years ago.
Here’s a listing of drives that still include that hardware write protection, along with some other options that might work though not as well. This listing is based on reports from several discussion boards in 2009-2010 as well as a list prepared and maintained by c’t Magazine (German) (or via Google Translate). Where available I provide links to the manufacturers and possibly to stores where the drives are available. Please comment with any corrections or additional drives to be added to the list.
USB Flash Drives with Hardware Write Protection
There are currently only seven models from four manufacturers readily available in the USA; I don’t have good data for what’s available outside the USA but will include any drives that I’m aware of regardless of US availability. Links to online suppliers are at the end of this article. There can be wide variations in speed between drives (e.g. USB Flash Drive Comparison – 21 Tested and Compared, which does not include any of the drives listed here but is informative), so check speed ratings and reviews where available. I mention some speed tests reported to USB Flash Drive Speed Tests below, if you have a flash drive feel free to check that website, test the drive and report the results.
There is a list with links to online stores that carry these drives at the end of this article. Drives not included in that list are ones that I didn’t find online sellers for. The stores used are Amazon, Newegg and the multi-store aggregator Google Products.
I have found very few of these drives in retail/physical stores. I’ve seen the Imation Clip in a few places that catered to students and the Imation Pivot and Swivel (both older model and newer) are carried in the CDW showroom near Chicago; beyond that I have not found the other drives locally available. The national computer (TigerDirect/CompUSA, Frys) and electronics (Best Buy) chains don’t list most of these drives as available online and for the most part don’t seem to carry many drives from these manufacturers at all (TigerDirect/CompUSA carries the Kanguru Defender Elites).
Hama
The Hama FlashPen “Fancy” (2GB, 4GB, 8GB, 16GB) appears to be primarily available in Europe. Only the 16GB gives speed figures, and its read speed of 6MB/sec seems low. According to c’t (link above) these are the same as the TrekStor USB-Stick CS described below.
Warning Note: Based on the experiences (April 2010) of the c’t editors, the pictures of the Hama drives are incorrect and only a small percentage have a write-protect switch.It’s not clear to me whether this also applies to the TrekStor drive; it’s possible that the early Hama drives were resold TrekStor drives and the later ones are manufactured separately.
Imation
Imation has two product lines with write protection switches, the Pivot (now discontinued) and the Clip. These should be widely available online and might be available in some stores. The Pivot appears to be the physically smallest of the available drives with write protection; the Clip is smaller and will fit tighter spaces but has a large protective carrier. The Pivot Plus does not list a hardware write protect switch on the website but does in the brochure; it also utilizes hardware-based encryption that may cause it to be incompatible with non-Windows systems.
Imation’s Swivel (not Swivel Pro) line used to have a write protect switch but it appears to have been removed on the current versions. The older versions have a gray/silver body, a dark swivel and a small LED on the side opposite the write-protect switch; the newer version without the write-protect switch has a black body, a black swivel and a LED in the center. Note that the Swivel Pro line resembles the older Swivel line but has a LED in the center and does not have a write-protect switch. Because of this change I do not recommend purchasing the Swivel online unless you’ve seen a picture of the actual product you’re getting.
Imation’s Defender line claims protection against malware in some models, but that appears to be based on requiring Windows or Mac encryption software to even access the drive. The user guide for the Defender F100/F150 does not mention hardware write protection, only the encryption software. The Defender F50 Pivot flash drive might have a hardware write protection switch – the Imation website shows a picture with one but does not mention it in the drive specifications; searches for the Defender F50 drive elsewhere turn up a variety of different images indicating that there may be multiple models available so I can’t recommend purchasing sight-unseen.
Imation does not provide read/write speed information on their website. Third-party testing of a 1GB Clip indicated a read speed of ~17MB/sec and a write speed of ~6MB/sec.
Kanguru
The Kanguru FlashBlu 2 includes a write-protect switch on the side. Capacity up to 128GB, read speed up to 20MB/sec and write speed up to 13MB/sec. The older FlashBlu drives (silver instead of blue) might have a switch based on the answer to a knowledgebase question, but there’s no other information about them online. Some vendors may still have the older drives.
Kanguru’s Defender Elite includes a write-protect switch and hardware encryption, but may not be compatible with all operating systems if encryption is used.It’s not clear whether it can be used without the encryption, but it’s expensive for a plain flash drive because you’re paying for the encryption hardware. The Defender Elite lists read speeds of 28-33MB/sec (20-33 for 32-64GB) and write speeds of 10-13MB/sec.
PQI
Most of PQI’s U339 model line (including the U339, U339XT, U339 Pro, U339H and U339S but NOT including the U339V) has a write protect switch in the endcap. I’ve seen cautions that the switch is somewhat fragile, and it may not be well-labeled but “With PQI logo facing upwards puch the switch to the right to prevent write / delete.”
PQI does not provide complete speed information on their website.
- The U339XT is listed as having a read speed up to 32MB/sec and a write speed up to 5MB/sec.
- The U339 Pro is listed as having a read speed up to 30MB/sec and a write speed up to 20MB/sec.
- The U339H is described as having “dual channel technology” and being “one of the fastest USB flash drives currently on the market” but does not provide actual speed information.
- The U339V (USB 3.0, 8-64GB) does not list a write-protect switch in its features, and no switch is visible in the photos they provide.
RITEK
RiDATA EZDrive Slider (ID10) and Twister (ID15) models both have write protection switches. The Twister’s appears to be on the side of the drive; the Slider’s appears to be next to the slider button which means it’s protected when the slider is closed. Reviews of these are mixed, I’ve seen complaints about write speed so check the stats or reviews first if you’re going to be moving a lot data.
RITEK does not provide speed information on their website.
Others
Trekstor (from c’t) – German manufacturer. USB-Stick CS product line features a write-protect switch (the same models can also be purchased in bulk with your logo printed on them as the USB-Stick yourLogo in quantities of 100+). Limited availability online. Website is multi-language and includes an interactive map showing countries with distributors. The TrekstorUSA (Thumbdrive) and Trek2000.com.sg websites do not appear to have been updated for 5-6 years.
Buffalo FireStix Type R (from c’t) – not listed on their website, but reportedly still available. Limited availability online. FireStix-branded RAM appears to be sold in Europe but not in the USA, but the European sites don’t list the flash drives. Flash drive part numbers for 2/4GB appear to be RUF2-R2G-S and RUF2-R4G-S.
I’ve seen mention of drives from Maxell with hardware write protection, but they do not list such drives on their USA website. If they are still available or are available internationally, please contact me with availability and part/model numbers. Ap.Tech is listed as having drives, but their website is nothing but a Flash intro.
Transcend sells industrial flash drives with write protect switches, these will likely need to be purchased directly from them. These drives do not have a standard USB plug, they are designed to connect to a 10-pin USB socket on a motherboard (take a look at the motherboard connector for front-panel USB ports on a regular PC for an example). Their product listing page is at http://www.transcendusa.com/Products/Modlist.asp?CatNo=122 for the USA, but they are also available from other international sites. Before purchasing read through the datasheet for the drives, available on Transcend’s website(s).
Victorinox SwissFlash (combination pocket knife & flash drive) drives are available but expensive. I’ll have more details up soon.
Opti3 / EasyDisk.com / EZDisk.com lists drives in capacities up to 4GB, but does not appear to have actually been updated since 2004. If you wish to place an order for a few 4GB drive for only $370/each, I’m sure they’ll manage to get drives of that capacity with write protect switches to you even if they have to buy Kanguru drives for $20/each from Amazon.
SD Cards – Not Recommended
SD Cards, while they have a write-protect switch, are actually no good for this purpose because it’s not actually hardware write protection – at best the card reader sends a signal to the operating system that the drive should be treated as read-only. The write-protect switch on the cards is read by a sensor that’s part of the card reader, and the card reader then passes along to the operating system whether the card is read-only. According to the specification from http://www.sdcard.org/:
A proper, matched, switch on the socket side will indicate to the host that the card is write-protected or not. It is the responsibility of the host to protect the card. The position of the write protect switch is unknown to the internal circuitry of the card.
Basically this means that either a) cheap card readers that lack the sensor or b) operating systems or malware that don’t respect the “please don’t write to this disk” flag can write to the drive. While this may not be likely, it’s also not as secure as you might think based on the presence of that switch.
Other Card Formats
There are some “Industrial” CompactFlash cards that include a hardware write protect switch, but they have limited availability. They are made by PQI and RITEK/RiDATA.
The earliest Sony MemorySticks had a hardware “Lock” switch, but it disappeared around the same time the capacity exceeded 128MB.
Software Tricks – Last Resort
There are a few software approaches that you can use in a pinch, but they’re mostly Windows-specific and it may be possible to bypass them – even if it seems unlikely.
Looking for a USB Flash Drive with Read Only or Write Protect Switch describes how to create a customized U3 partition based on an ISO file that will mount as a virtual CD-ROM. This will prevent items from being deleted from that virtual CD, but is not ideal for a system cleaning disk because the second partition can still be written to and infected. In addition, changing the contents of the protected area is a multi-step process that involves creating/updating an ISO file that is then used to re-create the U3 area on the flash drive.
USB Flash Drive Write Protection describes how the Windows Registry DWORD value WriteProtect in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies key controls whether USB devices are writable or write-protected. A value of 0 (zero) allows writing to USB devices; a value of 1 blocks writing to USB devices. Changes may take effect after a logoff/logon, but will certainly take effect after a restart. There are several drawbacks to this approach: it might be possible for software to bypass it, it blocks writing to all USB devices, it doesn’t take effect immediately – it requires at least a logoff/logon and possibly a system restart and you have to undo your changes because it affects all USB devices not just your flash drive.
Several applications (shareware and free) and instruction sets simplify the process of write protecting by filling up the disk by simply creating temporary files to consume all available free space on the drive. If there’s no space to create even a small autorun.inf file, it’s difficult to infect the drive since it won’t run items by default when the drive is connected to a PC. This is probably better than nothing since it will stop some infections, but it may also give a false sense of security – it’s not complete security. One of the several sites with instructions for this is Raymond.CC’s Create Fake Dummy File on USB Flash Drive to Enable Write Protect and Prevent Modification.
I’ve seen instructions for protecting the files on a drive by reformatting to NTFS, then removing all permissions except a very limited set. Much like filling the drive to capacity, this may work against some malware but it’s not 100% protection. Setting this up also depends on the which version of Windows you’re running (assuming that’s what you’re using) – non-business versions may not provide access to the security settings needed, and non-Windows systems will likely either ignore the security or not be able to read the drive. This also makes it more important to tell Windows to eject the drive before removing it, because it’s more likely that Windows will be waiting before writing changes to the drive.
Store Links
Here are links to these drives at major online stores or price-checking sites (Amazon, Newegg, Google Shopping). Google Shopping may get you the best price by a couple of dollars unless you’re getting free shipping from Amazon (or have Amazon Prime), but you may have to poke around a bit. If I didn’t list a store, they didn’t have any of the products when I created this listing, this includes TigerDirect and Fry’s Electronics. I was not able to find listings for the Trekstor or Buffalo products. This listing is US-targeted; internationally check with your regular purchasing options.
Hama FlashPen Fancy: @Amazon.de, @Amazon.co.uk and probably at other EU Amazon sites in various sizes. Images are reportedly incorrect, most drives do not have write-protection.
Imation Clip: @Amazon, @Google Shopping
Imation Pivot: @Amazon, @Google Shopping
Imation Swivel and Defender F50: Buy in-store if available due to product line variations described above.
Kanguru FlashBlu II: @Amazon, @Google Shopping
Kanguru Defender: @Amazon, @Google Shopping
PQI U339: @Amazon, @Google Shopping
PQI U339 Pro: @Google Shopping
PQI U339H: @Newegg, @Google Shopping
PQI U339S: @Google Shopping
RITEK RiDATA Slider: @Amazon, @Google Shopping
RITEK RiDATA Twister: @Amazon, @Newegg, @Google Shopping
Revisions
2010-03-15 added Kanguru drives, minor text tweaks. Added drive speed information where available.
2010-03-16 added notes about drive-filling and NTFS options
2010-03-18 minor note about older Kanguru drives
2010-03-29 updated with notes about in-store availability
2010-03-30 added Hama FlashPen Fancy, mention of Victorinox SwissFlash
2010-04-10 Noted link between Hama FlashPen Fancy and TrekStor USB-Stick CS
2010-05-04 Added Google Translate link to c’t FAQ, noted problem with Hama drives (from c’t)
2010-08-27 Added Imation Defender
2011-03-06 Removed Imation Pivot
2011-08-07 Added note about PQI U339V line not supporting write protect, removed note about Amazon affiliate program (no longer available in my state).
2011-08-19 Added Transcend industrial flash drives which use USB communications but connect to USB headers on a motherboard instead of to USB ports.
2012-01-11 Added Opti3 / EasyDisk / EZDisk for some level of completeness.
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The idea that the SD-card write-protect tab does not actually write-protect is just breathtaking! I mean, how could they screw that up? I suppose a real switch would be less reliable than a fake switch, but only if we do not care about write-protection reliability, which is the whole point of having the “switch” in the first place!
However, there may be a possibility not mentioned in: “either a) cheap card readers that lack the sensor or b) operating systems or malware that don’t respect the “please don’t write to this disk” flag can write to the drive.”
The actual phrasing (if we can trust it) is: “It is the responsibility of the host to protect the card.”
But in the case of a USB card reader, said “host” may be the hardware USB controller, and not necessarily the malware-subverted OS software. Perhaps some USB card reader designs effectively *do* provide the hardware protection we seek. It is not clear to me how to prove (or disprove) that.
Way back in ancient history, remember write-protect tabs or switches on floppy drives? They only worked on well-behaved software too.
I just saw some information on a reasonably-priced ($20-25) USB hard drive enclosure with a hardware write protect switch.
The ACARD ACP-2127 (via TinyApps.org)holds a 2.5″ SATA drive, but the website doesn’t have a lot of technical information. Does anyone have information on whether this is an actual write blocker or if it’s just setting a read-only flag for the operating system?
There are multiple other such products available, but they tend to be both larger and significantly more expensive – they’re primarily sold into the computer forensics market, where it’s vital that not a single bit be changed on hard drives being investigated. I haven’t paid a lot of attention to those, but I don’t recall seeing any that were sized to be used as portable storage.
[...] A very good overview of currently available drives is presented in the article “List of USB Flash Drives with Hardware Write Protection” (Fencepost Software & Consulting) http://www.fencepost.net/2010/03/usb-flash-drives-with-hardware-write-protection/ [...]
Have you seen the read-only version of the Addonics Mini DigiDrive, model AESDD12U2WP?
http://www.addonics.com/products/flash_memory_reader/mini_digidrive.asp
It’s old but it works and it keeps viruses off my camera’s memory card. It’s still available for $27.
Have you seen any other readonly Flash memory card readers?
Saved my life with this article thank you!! I’m looking to protect my pc inside and out with a live cd or USB pen drive, a bios write protect a pci graphics card with write protect and sound with write protect. Is there anyone who could suggest hardware pci devices and a motherboard that will make this possible? just a suggestion maybe you should write an article that can make a pc 100 percent safe from all virii and firmware root kits..ect again great article! Thanks!
I found this cnet review list with hardware protected usb’s, hope it helps.
http://reviews.cnet.com/usb-flash-drives/?filter=502909_14791771_&tag=mncol
Thanks! They appear to have most of the same things I have listed here, but it’s good to know of another listing to keep an eye on. The only surprise was a Verbatim drive specifically for Macs, but that turns out to be a drive with Mac-specific software for encrypting part of the drive.
The Imation Defender F50 Pivot 8GB photos I saw at newegg showed the write protect switch, and had the UPC of 26658. UPCs for the Pivot and Defender F50 are identical–Defender F50 is just marketing.
http://www.imation.com/en-us/Imation-Products/USB-Flash-Drives–Accessories/Pivot-Flash-Drive/
http://www.imation.com/en-us/Imation-Products/Defender-Collection/F-50-Pivot/
I was curious about performance so I used crystaldiskmark 3.00 64b on my AMD SB600 on the Pivot, Slider, and Flashblu 2 8GB. The Slider has the worst configuration from the factory, and the Pivot looks like it has a somewhat weak controller since I could never match or exceed the original performance after formatting. After formatting away the factory offsets, offsets are either 1024 KiB, or 4032 KiB (Kanguru), filesystem is FAT32.
[Sequential read MiB per sec / Sequential write MiB per sec]
Imation Pivot,
0 offset,
22-23 / 11-13 factory,
2 KiB allocation unit for best seq write = 21-22 / 13
Kanguru Flashblu 2,
4032 KiB offset,
26 / 14 factory,
16-64 KiB allocation unit for best seq write = 26 / 15
Ridata Slider,
0 offset,
22 / 7 factory,
8 KiB allocation unit for best seq read = 24 / 11,
2 KiB allocation units for best seq write 22 / 12
Greetings,
On a related note, might you know of any providers of write-once, read-only USB drives, preferably in thin formfactor that would fit nicely on a keyring? Think of it as a LiveCD in a very small USB stick.
Thanks
Sorry I never posted a reply to this.
I have seen one “giveaway” flash drive in a thick credit-card size format that showed up with both a writable and non-writable partition, but I’m not sure if it was software, hardware or a combination of the two nor do I know if it could be made bootable. It may be a case of partitioning the drive, writing a CD-based filesystem to one partition, etc.
Some of the methods for creating bootable Linux distributions involve basically putting an ISO on the flash drive then booting to that, but I don’t know the technical details. One place with information on doing this is the “Alternate Install (Ubuntu 9.10)” section of https://help.ubuntu.com/community/USB%20Installation%20Media , which notes that “in this variant, the USB stick only contains a few boot-supporting files and the raw .iso image.”
If you’re doing a large volume of these you can probably get them pre-burned on non-writable drives as a custom order.
Finally, for small volumes you might be able to get away with using one of the drives listed here, but doing your own custom case for it and replacing the plastic outer shell with one that covers the switch.
Thank you! Thank you! Thank you!
Just the info I needed.
Hi,
no replies listed since you were linked on
Security Now Netcast / Podcast show notes
in June 2011.
http://wiki.twit.tv/wiki/Security_Now_304
http://wiki.twit.tv/wiki/Security_Now_305
Mifune
The 64GB PQI U339V doesn’t look like it has the write protect switch. Maybe you could re-word your section on this product line to make it obvious ?
Done, thanks for the update!
Transcend USB Flash Modules have a write protection switch.
http://www.transcend.nl/Products/Modlist.asp?CatNo=122
Thanks for this, I updated the list to include the Transcend USA website along with some notes about the drives (not truly USB drives like the rest of the items on this page).
Alan, thanks for a great resource.
I have a question, why do you think the manufacturers do not make many of these write protected drives? Ie SanDisk. do you think there is a specific reason for this?
Perhaps they’re in collaboration with the anti-virus companies… Just a thought…
Regards
It’s not worth the additional expense to them – the number of people who actually use the write-protect switch on the drives is low enough that they’re not a viable market by themselves. If you’re not targeting to the small community that wants that feature, adding the feature adds a few cents per drive spread across hundreds of thousands (millions?) of drives, resulting in a manufacturing cost that’s a few hundred thousand higher with no significant increase in sales due to the feature.
For the smaller manufacturers like Kanguru, I think they have a slightly higher-end reputation and possibly a more dedicated customer base, so their drives are “premium” devices that cater more to niche markets. When you’re catering to niche markets and priced accordingly, the incremental increase in manufacturing price is more acceptable because your better feature set is what brings customers to you – you’re selling a premium product not a commodity.
Thanks Alan, you are right.
I got the Kanguru FlashBlu2 drives (8GB) on Amazon. They work very well and I am pleased. Also a lot faster than some Sandisk Cruzers that I have. Sandisk was around 3-4 MB/s and Kanguru about 9 MB/s. Very happy with Kanguru so far
As far as uk is concerned I’ve found this Swivel 16gb (http://www.amazon.co.uk/Imation-Swivel-Lanyard-Password-protection-Windows/dp/B001GT5FQ8) that in combination to an pdf describing imation reference ids (http://partner.imation.com/cdlpub/servlet/CDLServlet?p_file_id=12105) seems to be a hardware enabled read-only switch and a cheap one. Awaiting delivery to let you know.
That looks like the older style of Swivel – if the one you get has the LED centered on the end instead of on the side and is black instead of grey, it’s the new style without the switch. That PDF is interesting since it also lists the Pivot as having a write-protect switch, but Imation’s [USA] web site no longer lists the Pivot – just the Pivot Plus.
Just got them (Greek land mail is the definition of speed) after sending these to a cousin in London and then to Greece and happily these are the versions wanted, i.e. with the hardware switch.
Alan:
Thank You for the article as it has been a great help. I must say though that the PQI drives you mentioned have failed to actually be fully write protected in a simple situation that arose through a mistake on my end. Several days ago I was using the Windows utility diskpart to make some Windows 2008 Server Install USB sticks and I selected the wrong USB stick by mistake, with the stick being the PQI U339 4GB. Even though it was set to write protected and when you right clicked the individual folders within the PQI U339 the delete option in the context menu was not available, the diskpart utility was still able to destroy the data using the clean command. Even though it took a long time diskpart returned error:
“DiskPart has encountered an error: The semaphore timeout period has expired.
See the System Event Log for more information.”,
but Windows couldn’t read from the PQI U339 4GB drive anymore and I had to simply reformat it.
When I tried the same thing with the Kanguru Flashblu II, diskpart returned an error message immediately:
“DiskPart has encountered an error: The media is write protected.
See the System Event Log for more information.”
and the data remained intact.
I’ve been using the PQI drives for troubleshooting and virus removal for years, until they seemingly became unavailable from the major US vendors (Newegg & etc.) after which I found your great article and started using Kanguru USB sticks.
I know this is an old article of yours, but I was hoping you could comment on my observation.
Glad it was helpful – I update the article periodically based on what products are out there (or no longer so), but there hasn’t been much in terms of new devices lately.
I’m surprised that the write protection on the PQI drive didn’t fully work, but since it’s presumably partially implemented in software on the drive it may be that some operations that modify the drive aren’t actually checking. It sounds like a mixture of Windows diskpart trying despite the write-protected status and the PQI drive not catching it. I’m not up to speed on USB drive connections, but I suspect that there are two parts – reporting the drive as read-only to the OS and rejecting any attempts to write to it if the OS ignores that information. Sounds like only the first part of that happened correctly with the PQI drive.
I’m a bit disappointed that the new USB 3 drive from Kanguru doesn’t include a write-protect switch, but perhaps if/when they release USB 3 drives in their Defender line they’ll add that feature.
I appreciate your swift response and feel relieved that you confirmed some of my suspicions. Neither do I have a clue on how USB drive connections work or how write-protection is implemented, but had it not been for the slight error on my end, I would not have started wondering how well the write-protection really works.
After all the main point of the “write-protection” is to prevent viruses and other malicious software from modifying the contents of the USB memory device and if “diskpart” can do it, I would assume that malicious code could do the same thing.
I was also disappointed that the Kanguru USB 3.0 drives didn’t include a write-protection switch, but I assumed that was due to USB 3.0 not being quite mainstream yet. In my opinion the placement of the write-protection switch was better on the PQI U339, because it was tucked away in the rear end and you needed a paperclip to move it. On the Kanguru Flashblu II one has to be careful not to mistakenly move the switch during insertion/removal.
I have found your blog after googling “usb flash drive with lock switch” and have read some of your other posts since. You don’t seem to post often like some of the other tech-gurus, but it’s the quality that matters and not the quantity. Keep up the good work!
http://www.qumo.ru/catalogue/products/51.xhtml
qumo yin&yan 4 – 16gb write/read very slow…
Sorry i do not the English version of the site, but the defense a mechanical write protect switch is exactly ..
[The original submitter included a link to what appears to be a storefront where these drives are available - http://torg.mail.ru/usbflash/qumo-yin-yan-16gb-id140176/?tab_id=5 ]
Thanks for letting us all know about this – useful for folks over there. I didn’t find any sign that these are available outside Russia & possibly other former-Soviet countries. I’ve added in the shopping link you included in a separate message.
I did a little digging on the manufacturer’s site using Google’s translation and it looks like the Yin Yang is the only model with a write protection switch (and even that is based on the picture of the packaging and the almost invisible switch itself in one picture.
Again, thanks for pointing these out!