MALICIOUS
256
Risk Score
Malware Insights
MITRE ATT&CK
T1059.007 JavaScript
T1203 Exploitation for Client Execution
T1566.001 Spearphishing Attachment
This PDF file was flagged as malicious by multiple heuristics, including critical findings for JavaScript exploit clusters and a large comment-padded eval stager. The embedded JavaScript is heavily obfuscated but the presence of eval() and String.fromCharCode() indicates it is designed to download and execute a second-stage payload. The ClamAV detection name 'Pdf.Exploit.Agent-36086' further supports this assessment.
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.js9a44e7141d9b1840b827ef34fbed231ece7212936d6d1edba57afcf5cd697584 |
pdf-javascript-stream | PDF /JS object 6 at offset 0x143 | 626356 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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stream_002_off0001d866.bin4495fcb597da98b5b50415291bf82ddf4a1b999eee56b56a2c6ccf2277aa5c49 |
decompressed-pdf-stream | PDF FlateDecoded stream at offset 0x1D866 | 200 bytes |
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