MALICIOUS
316
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 utilizes `eval()` and `unescape()` functions to decode and execute malicious code. This script is designed to exploit vulnerabilities within the PDF viewer, leading to the execution of a second-stage payload. The presence of the 'Pdf.Exploit.Agent-35912' ClamAV signature further confirms its malicious nature.
Machine Learning
- Nyx PDF Classifier malicious score 1.0000
Heuristics 9
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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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Annotation subject percent-decoding eval stager critical PDF_ANNOT_SUBJECT_MARKER_EVAL_STAGEROpenAction JavaScript forces annotation enumeration, reads an annotation /Subject payload with getAnnots(), rewrites marker bytes into percent escapes, decodes it with unescape(), and dispatches it through eval. This is a high-confidence exploit-kit staging pattern. It is intentionally not mapped to CVE-2009-1492 unless getAnnots() itself carries the crafted integer or long argument shape for that vulnerability.
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ClamAV: Pdf.Exploit.Agent-35912 critical CLAMAV_DETECTIONClamAV detected this file as malware: Pdf.Exploit.Agent-35912
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eval() call high PDF_EVALeval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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unescape() call high PDF_UNESCAPEunescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
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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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syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCANPDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed 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 3
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
javascript_obj0007_000.js7218a1c68060953321573daa035b16f5f32928ce25a9eb656690dbe78cd9464e |
pdf-javascript-stream | PDF /JS object 7 at offset 0x1A2 | 201 bytes |
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Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 2 eval/decoder/string-building token(s).
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legacy_pdfkit_stage_000.jsf092e4a6f14488728b9c1767615f6f265caf62f745bcf6365f30f7726b42f05c |
deobfuscated-js | repeated-marker hex decoded JavaScript at offset 0x2BC | 10448 bytes |
|
Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
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deobfuscated.js298a72315375d72c6e5d01b4291a27b4483aafa6de7d626a9846ab8a17b6fe8b |
deobfuscated-js | PDF JavaScript deobfuscation pass | 38820 bytes |
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Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
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