![\"\"](\"https:\/\/media.kasperskydaily.com\/wp-content\/uploads\/sites\/91\/2021\/10\/11143407\/what-is-spookjs-1.png\")
Spectre g\u00fcvenlik a\u00e7\u0131\u011f\u0131 logosu<\/p><\/div>\n
Bir kullan\u0131c\u0131, bir internet sitesinde oturum a\u00e7mak i\u00e7in parolas\u0131n\u0131 girdi\u011finde arkada, parola do\u011fruysa bir dizi komut, do\u011fru olmamas\u0131 durumunda ise ba\u015fka bir dizi komut y\u00fcr\u00fct\u00fcl\u00fcr. Bununla birlikte \u2014 dallanma \u00f6ng\u00f6r\u00fcs\u00fcn\u00fcn devreye girdi\u011fi yer tam da buras\u0131d\u0131r \u2014 do\u011fru olup olmad\u0131\u011f\u0131na ili\u015fkin geri d\u00f6n\u00fc\u015f almadan \u00f6nce CPU, b\u00fcy\u00fck olas\u0131l\u0131kla \u00e7al\u0131\u015ft\u0131rmas\u0131 gerekti\u011fini d\u00fc\u015f\u00fcnen komut setini y\u00fcr\u00fctmeye ba\u015flar.<\/p>\n
\u00d6rne\u011fimizde, parola daha \u00f6nce y\u00fczlerce kez do\u011fru girildiyse, CPU bu sefer de farkl\u0131 olmayaca\u011f\u0131n\u0131 varsayar. CPU\u2019nun \u00f6ng\u00f6r\u00fcs\u00fc do\u011fru \u00e7\u0131karsa, kullan\u0131c\u0131 bir performans art\u0131\u015f\u0131 sa\u011flam\u0131\u015f olur. Yanl\u0131\u015f \u00e7\u0131karsa da, CPU varsay\u0131msal olarak y\u00fcr\u00fct\u00fclen komutlar\u0131 atar ve di\u011fer komut setini \u00e7al\u0131\u015ft\u0131r\u0131r.<\/p>\n
Bir Spectre g\u00fcvenlik a\u00e7\u0131\u011f\u0131 sald\u0131r\u0131s\u0131nda, program\u0131n eri\u015fimi olmayan bir veri alan\u0131n\u0131 okuma giri\u015fiminde bulunulur. Sald\u0131r\u0131n\u0131n ilk a\u015famas\u0131nda, a\u00e7\u0131k eri\u015fim veri alanlar\u0131na \u00e7oklu \u00e7a\u011fr\u0131lar yap\u0131l\u0131r, bu sayede dallanma \u00f6ng\u00f6r\u00fc sistemi yasakl\u0131 okuma i\u015flemini de ger\u00e7ekle\u015ftirecek \u015fekilde \u201ce\u011fitilir\u201d. Dallanma \u00f6ng\u00f6r\u00fcs\u00fc kullan\u0131larak CPU, ger\u00e7ekten okumas\u0131na izin verilen verileri okumak isteyen programa al\u0131\u015fk\u0131n oldu\u011fu i\u00e7in i\u015flemi \u00f6nceden ger\u00e7ekle\u015ftirir. Ancak yap\u0131lan bir kontrol, program\u0131n verilere eri\u015fiminin yasak oldu\u011funu ortaya \u00e7\u0131kar\u0131r ve bunun sonucunda varsay\u0131msal olarak y\u00fcr\u00fct\u00fclen hesaplamalar at\u0131l\u0131r. Buraya kadar her \u015fey yolunda \u2014 ancak CPU taraf\u0131ndan okunan veriler bir s\u00fcre CPU\u2019nun kendi belle\u011fi olan \u00f6nbellekte saklanmaya devam eder.<\/p>\n
\u0130\u015fin ilgin\u00e7 k\u0131sm\u0131 da bundan sonra ba\u015flar: CPU\u2019nun \u00f6nbelle\u011finden gizli verileri do\u011frudan okuman\u0131n hi\u00e7bir yolu olmad\u0131\u011f\u0131ndan, k\u00f6t\u00fc niyetli s\u00fcre\u00e7, bu verileri \u00e7almak i\u00e7in yan kanal sald\u0131r\u0131s\u0131(side-channel attack) ad\u0131 verilen bir sald\u0131r\u0131 ba\u015flat\u0131r. Bu sald\u0131r\u0131da belirli bilgilere eri\u015fim h\u0131z\u0131 \u00f6l\u00e7\u00fcl\u00fcr. Veri g\u00f6rece olarak k\u00fc\u00e7\u00fckse, bu, verilerin \u00f6nbellekte tutuldu\u011fu anlam\u0131na gelir. B\u00fcy\u00fckse, normal RAM\u2019den y\u00fcklenir. Bir dizi okuma denemesi, gizli bilgilerin s\u0131zmas\u0131na neden olur.<\/p>\n
Sonu\u00e7 olarak ya\u015fanan, tek \u00e7\u00f6z\u00fcm\u00fc dallanma \u00f6ng\u00fcr\u00fcs\u00fcn\u00fcn tamamen devre d\u0131\u015f\u0131 b\u0131rak\u0131lmas\u0131 olan ve dolay\u0131s\u0131yla performans\u0131 ciddi \u015fekilde etkileyen temel bir CPU hatas\u0131d\u0131r. Bununla birlikte, Spectre sald\u0131r\u0131lar\u0131nda:<\/p>\n
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- Sald\u0131rgan\u0131n, hedef bilgisayarda veya mobil cihazda program kodunu \u00e7al\u0131\u015ft\u0131rabilmesi,<\/li>\n
- Sald\u0131r\u0131n\u0131n, ba\u015far\u0131l\u0131 bir sald\u0131r\u0131 i\u00e7in gereken ko\u015fullar\u0131 olu\u015fturacak \u015fekilde kodlanm\u0131\u015f belirli bir hedef programa sahip olmas\u0131,<\/li>\n
- Sald\u0131r\u0131 ba\u015far\u0131l\u0131 bir \u015fekilde ger\u00e7ekle\u015ftirilmi\u015f olsa bile, verinin \u00e7\u0131kar\u0131lmas\u0131n\u0131n olduk\u00e7a yava\u015f (saniyede onlarca veya y\u00fczlerce bayt) ve okuma hatalar\u0131n\u0131n imkans\u0131z olmaktan \u00e7ok uzak olmas\u0131,<\/li>\n
- Genel olarak, parolalar, \u015fifreleme anahtarlar\u0131 vb. gibi ele ge\u00e7irilmesi ama\u00e7lanan gizli verilerin \u00e7al\u0131nmas\u0131n\u0131n bir dizi ko\u015fula ba\u011fl\u0131 olmas\u0131 gibi s\u0131n\u0131rlamalar s\u00f6z konusudur.<\/li>\n<\/ul>\n
Spook.js \u2014 Spectre v1\u2019in ger\u00e7ek hayattaki uygulamas\u0131<\/h2>\n
Spectre\u2019nin o kadar da tehlikeli olmad\u0131\u011f\u0131 sonucuna varabiliriz. Sonu\u00e7ta, bir sald\u0131rgan hedef bilgisayarda kod \u00e7al\u0131\u015ft\u0131rabiliyorsa, ayr\u0131cal\u0131klar\u0131 y\u00fckseltmek ve verileri \u00e7almak i\u00e7in i\u015fletim sistemindeki veya y\u00fckl\u00fc programlardaki \u00e7ok say\u0131daki g\u00fcvenlik a\u00e7\u0131\u011f\u0131ndan birini kullanmak sald\u0131rgan a\u00e7\u0131s\u0131ndan \u00e7ok daha kolay bir tercih olurdu.<\/p>\n
Bu do\u011fru olsa da g\u00fcn\u00fcm\u00fcz web sayfalar\u0131nda, kullan\u0131c\u0131n\u0131n bilgisayar\u0131nda ve taray\u0131c\u0131da y\u00fcr\u00fct\u00fclen b\u00fcy\u00fck miktarda program kodu yer al\u0131yor. Spook.js sald\u0131r\u0131lar\u0131 da Spectre v1 g\u00fcvenlik a\u00e7\u0131\u011f\u0131ndan bu \u015fekilde yararlan\u0131yor: Vir\u00fcsl\u00fc bir sayfa y\u00fckleniyor, taray\u0131c\u0131 kodu y\u00fcr\u00fct\u00fcyor ve siber su\u00e7lu gizli verileri \u00e7al\u0131yor.<\/p>\n