MALICIOUS
256
Risk Score
Malware Insights
MITRE ATT&CK
T1059.007 JavaScript
T1203 Exploitation for Client Execution
T1566.001 Spearphishing Attachment
This PDF file contains obfuscated JavaScript that utilizes eval() and String.fromCharCode(), common techniques for executing malicious code. The critical PDF_JS_EXPLOIT_CLUSTER and ML_NYX_PDF_MALICIOUS heuristics, along with the ClamAV detection of 'Pdf.Exploit.Agent-36086', strongly indicate malicious intent. The JavaScript is designed to download and execute a second-stage payload, a typical behavior for PDF-based exploits.
Machine Learning
- Nyx PDF Classifier malicious score 1.0000
Heuristics 8
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PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTERPDF 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.
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ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTIONClamAV detected this file as malware: Pdf.Exploit.Agent-36086
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eval() call high PDF_EVALeval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVALPDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
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JavaScript action low PDF_JAVASCRIPTPDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
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Embedded JS stream low PDF_JSPDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
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String.fromCharCode low PDF_FROMCHARCODEString.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
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Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGEOne 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.
| Filename | Kind | Source | Size |
|---|---|---|---|
javascript_obj0006_000.js785777f0c377f6e1d5342f1ddae47ac63c9455c56b4c4ef91604090bb0ea0f02 |
pdf-javascript-stream | PDF /JS object 6 at offset 0x143 | 426008 bytes |
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Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).
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legacy_pdfkit_stage_000.jscecdb746c5186bc317ac242d4f3968ee221dc3456e15729d67e176d1ec477cb8 |
deobfuscated-js | double percent-decoded annotation JavaScript at offset 0x143 | 262144 bytes |
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Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 667 long base64-like blob(s).
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