{"id":12206,"date":"2016-05-26T07:00:56","date_gmt":"2016-05-26T11:00:56","guid":{"rendered":"https:\/\/www.kaspersky.com\/blog\/?p=12206"},"modified":"2019-11-15T06:56:41","modified_gmt":"2019-11-15T11:56:41","slug":"usb-battery-charging-unsecurity","status":"publish","type":"post","link":"https:\/\/www.kaspersky.com\/blog\/usb-battery-charging-unsecurity\/12206\/","title":{"rendered":"Charging your smartphone&#8217;s battery over USB can be dangerous"},"content":{"rendered":"<p>Chances are that each of us has found ourselves in a situation where our phone is dying and we have no charger on hand, but at the same time we desperately need to stay connected \u2014 to answer an important call, receive a text message or email, whatever.<\/p>\n<p>It is perfectly normal to look for any source of precious electricity on such occasion \u2014 any USB port would do. But is it safe? No. In fact, it can be dangerous: Over a USB connection someone can steal your files, infect your smartphone with something nasty \u2014 or even brick it.<\/p>\n<h3>Ride the lightning<\/h3>\n<p>Before we get to the problem of thieves, we must point out that not all electricity is equally good for your phone. The Internet is full of complaints, filed mostly by users who tried to charge their fancy phones by connecting them to aftermarket (or non-original) chargers. In some cases doing so turned the phones into quite expensive bricks. In the most bizarre cases, people holding the phone in their hands were seriously injured or <a href=\"http:\/\/www.theverge.com\/2013\/7\/15\/4524438\/apple-investigating-death-of-woman-allegedly-electrocuted-by-iphone-5\" target=\"_blank\" rel=\"noopener nofollow\">even killed<\/a>.<\/p>\n<blockquote class=\"twitter-tweet\" data-width=\"500\" data-dnt=\"true\">\n<p lang=\"en\" dir=\"ltr\">Teen dies after being electrocuted in her sleep while charging her iPhone <a href=\"http:\/\/t.co\/1YyPVHOhN0\" target=\"_blank\" rel=\"noopener nofollow\">http:\/\/t.co\/1YyPVHOhN0<\/a><\/p>\n<p>\u2014 Daily Mail Online (@MailOnline) <a href=\"https:\/\/twitter.com\/MailOnline\/status\/494817353642049536?ref_src=twsrc%5Etfw\" target=\"_blank\" rel=\"noopener nofollow\">July 31, 2014<\/a><\/p><\/blockquote>\n<p><script async src=\"https:\/\/platform.twitter.com\/widgets.js\" charset=\"utf-8\"><\/script><\/p>\n<p>Unfortunately, these may be more than just accidents. For example, last year we saw a twisted device aptly named USB Killer. It contained an impressive set of capacitors, housed in a USB-flash-drive-size frame, that would discharge 220 V into a USB port. Such discharge would destroy the USB port at minimum, and possibly fry the whole computer\u2019s motherboard in a worst-case scenario. We doubt that you\u2019d want to try your phone\u2019s durability in such a way.<\/p>\n<h3>Show me your files, baby<\/h3>\n<p>Secondly, USB ports were designed not just to provide charge, but also to transfer data. So whenever a mobile device is connected to a USB port, it attempts a handshake, during which it transmits some data. The most data-wasteful are phones based on Android platform 4.<i>x<\/i> and earlier \u2014 they connect in MTP (<a href=\"https:\/\/en.wikipedia.org\/wiki\/media_transfer_protocol\" target=\"_blank\" rel=\"noopener nofollow\">Media Transfer Protocol<\/a>) mode by default, exposing all of the device\u2019s files.<\/p>\n<p>On average, it takes more than 100 kilobytes of data just to tell the host system about the phone\u2019s files and folders \u2014 for reference, that\u2019s about the size of <i>Alice in Wonderland<\/i> e-book.<\/p>\n<p>Locking the phone will save you from such exposure \u2014 but, honestly, do you abstain from using the phone while it\u2019s charging? And do you always disconnect the phone from the USB port when you receive a text message, for example?<\/p>\n<p>Now, let\u2019s take a closer look at the data that is transmitted to the USB port even when the mobile is in \u201ccharging only\u201d (blocked) mode. The amount of data varies depending on the mobile\u2019s platform and the operating system of the host, but in any case it\u2019s more than \u201cjust charge, nothing personal\u201d \u2014 as we found out, this data includes device name, vendor name, and serial number.<\/p>\n<h3>Full access and beyond<\/h3>\n<p>You may think the data transmission issue is not a big deal, but the problem \u2014 as we\u2019ve discovered by looking into publicly available information about one specific vendor \u2014 is that they allow for <a href=\"https:\/\/securelist.com\/blog\/mobile\/74804\/wired-mobile-charging-is-it-safe\/\" target=\"_blank\" rel=\"noopener\">much more than specified by the system<\/a>.<\/p>\n<p>How is that possible?<\/p>\n<p>It is done by a legacy system of commands called <a href=\"http:\/\/www.zeeman.de\/wp-content\/uploads\/2007\/09\/ubinetics-at-command-set.pdf\" target=\"_blank\" rel=\"noopener nofollow\">AT-commands<\/a>. The AT commands were developed a few decades ago to enable the modem and PC communications. Later, the set was included in the GSM standard, and to this day it is supported in all smartphones.<\/p>\n<p>To give you an idea of what can be done using AT commands: They enable an attacker to get your phone number and download the contacts which are stored in the SIM card. Then, they can call any number \u2014 at your expense, of course. (And if you\u2019re roaming, such surprise calls may quickly drive your balance into the red.) Depending on your vendor, this mode can also open access to install any type of application \u2014 including malicious ones.<\/p>\n<p>All of the above is possible even if your smartphone remains locked!<\/p>\n<p>To sum up: Remember that you <a href=\"http:\/\/arstechnica.com\/security\/2016\/05\/beware-of-keystroke-loggers-disguised-as-usb-phone-chargers-fbi-warns\/\" target=\"_blank\" rel=\"noopener nofollow\">can never tell<\/a> what is on the other side of a normal-looking USB port. A USB port can be a system that gathers data about the devices that are connected to it, a flawed power source, a powerful capacitor, or a computer that installs a backdoor on your device. You simply cannot know before you plug in your device \u2014 so don\u2019t.<\/p>\n<h3>We have the solution (update: June 16, 2016)<\/h3>\n<p>Isn\u2019t there a better way? In theory, the solution is simple \u2014 you just need to block the data transfer and control the charge current. Is there a practical way to do that?<\/p>\n<p>Yes, there is! That\u2019s exactly what <a href=\"https:\/\/www.kaspersky.com\/blog\/pure-charger\/12315\/\" target=\"_blank\" rel=\"noopener noreferrer nofollow\">Kaspersky Lab\u2019s Pure.Charger<\/a> does. It\u2019s a device, about the size of a USB flash drive. It connects with a male jack to a USB port in a car, airplane, charging station, whatever; your mobile or tablet connects to the female USB port on the other side of the gadget. By default, no data is transferred through the device.<\/p>\n<p><a href=\"https:\/\/media.kasperskydaily.com\/wp-content\/uploads\/sites\/92\/2016\/05\/06015657\/5-1024x536.jpg\"><img decoding=\"async\" src=\"https:\/\/media.kasperskydaily.com\/wp-content\/uploads\/sites\/92\/2016\/05\/06015657\/5-1024x536.jpg\" alt=\"Pure.Charger: How to charge your smartphone in a public location without infecting it\" width=\"1200\" height=\"628\" class=\"aligncenter size-full wp-image-7312\"><\/a><\/p>\n<p>Although small, the device is not dumb. Powered by a smart microchip, the Pure.Charger boasts a touch screen that allows users to enable the data transfer mode with a natural swipe motion; you don\u2019t have to reconnect the mobile device to enable the data transfer with a port that you trust. It also remembers your choice \u2014 and location \u2014 if you pair it with the device via Bluetooth.<\/p>\n<p>Pure.Charger also protects your expensive mobile phone or tablet from electricity surges \u2014 it contains a power stabilizer and surge-protection circuits. In the worst-case scenario it will take the blow to protect your mobile. To learn more, visit the <a href=\"https:\/\/www.kickstarter.com\/projects\/1554074090\/purecharger\" target=\"_blank\" rel=\"noopener noreferrer nofollow\">product\u2019s web page<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Charging your smartphone\u2019s battery over USB can be dangerous: Thieves can steal your files, infect your smartphone with something nasty \u2014 or even brick it.<\/p>\n","protected":false},"author":595,"featured_media":12207,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5,2683],"tags":[105,1637,423,914,45,422,424],"class_list":{"0":"post-12206","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-news","8":"category-threats","9":"tag-android","10":"tag-dangers","11":"tag-mobile-devices","12":"tag-private-data","13":"tag-smartphones","14":"tag-threats","15":"tag-usb"},"hreflang":[{"hreflang":"x-default","url":"https:\/\/www.kaspersky.com\/blog\/usb-battery-charging-unsecurity\/12206\/"},{"hreflang":"en-ae","url":"https:\/\/me-en.kaspersky.com\/blog\/usb-battery-charging-unsecurity\/5445\/"},{"hreflang":"ar","url":"https:\/\/me.kaspersky.com\/blog\/usb-battery-charging-unsecurity\/3807\/"},{"hreflang":"en-us","url":"https:\/\/usa.kaspersky.com\/blog\/usb-battery-charging-unsecurity\/7195\/"},{"hreflang":"en-gb","url":"https:\/\/www.kaspersky.co.uk\/blog\/usb-battery-charging-unsecurity\/7242\/"},{"hreflang":"es-mx","url":"https:\/\/latam.kaspersky.com\/blog\/usb-battery-charging-unsecurity\/7163\/"},{"hreflang":"es","url":"https:\/\/www.kaspersky.es\/blog\/usb-battery-charging-unsecurity\/8368\/"},{"hreflang":"it","url":"https:\/\/www.kaspersky.it\/blog\/usb-battery-charging-unsecurity\/8258\/"},{"hreflang":"ru","url":"https:\/\/www.kaspersky.ru\/blog\/usb-battery-charging-unsecurity\/12039\/"},{"hreflang":"tr","url":"https:\/\/www.kaspersky.com.tr\/blog\/usb-battery-charging-unsecurity\/2142\/"},{"hreflang":"fr","url":"https:\/\/www.kaspersky.fr\/blog\/usb-battery-charging-unsecurity\/5710\/"},{"hreflang":"pt-br","url":"https:\/\/www.kaspersky.com.br\/blog\/usb-battery-charging-unsecurity\/6320\/"},{"hreflang":"ja","url":"https:\/\/blog.kaspersky.co.jp\/usb-battery-charging-unsecurity\/11562\/"},{"hreflang":"ru-kz","url":"https:\/\/blog.kaspersky.kz\/usb-battery-charging-unsecurity\/12039\/"},{"hreflang":"en-au","url":"https:\/\/www.kaspersky.com.au\/blog\/usb-battery-charging-unsecurity\/12206\/"},{"hreflang":"en-za","url":"https:\/\/www.kaspersky.co.za\/blog\/usb-battery-charging-unsecurity\/12206\/"}],"acf":[],"banners":"","maintag":{"url":"https:\/\/www.kaspersky.com\/blog\/tag\/android\/","name":"Android"},"_links":{"self":[{"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/posts\/12206","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/users\/595"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/comments?post=12206"}],"version-history":[{"count":2,"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/posts\/12206\/revisions"}],"predecessor-version":[{"id":30256,"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/posts\/12206\/revisions\/30256"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/media\/12207"}],"wp:attachment":[{"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/media?parent=12206"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/categories?post=12206"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kaspersky.com\/blog\/wp-json\/wp\/v2\/tags?post=12206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}