MALICIOUS
64
Risk Score
Malware Insights
MITRE ATT&CK
T1059.001 PowerShell
T1204.002 Malicious File
The PDF file was flagged as malicious by an ML classifier with high confidence. Static analysis revealed embedded JavaScript, including streams that use String.fromCharCode and syncAnnotScan primitives, indicating an attempt to decode and execute exploit code. The presence of obfuscated JavaScript files suggests the primary function is to download and execute further malicious content.
Machine Learning
- Nyx PDF Classifier malicious score 0.9998
Heuristics 5
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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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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. (identified after JavaScript deobfuscation)
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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_obj0004_000.jsb771a67801a2a024471cb29d8ce119b13dc98b5c56ef213dece7e1a5cc7b8bed |
pdf-javascript-stream | PDF /JS object 4 at offset 0xE1 | 1814 bytes |
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Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 1 eval/decoder/string-building token(s).
|
|||
numeric_charcode_stage_000.js4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d |
deobfuscated-js | numeric char-code string decoded JavaScript at offset 0xEF | 469 bytes |
|
Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 1 eval/decoder/string-building token(s).
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