PDF malware analysis — malicious · fe4b9a44f4c0b8fc

MALICIOUS

PDF

2.3 KB

MD5: bbb84e09e760e6b47541c2274d0b1f5b SHA-1: 9eca6a93867fb78794d766532db9cd4df429d94d SHA-256: fe4b9a44f4c0b8fc34ee5f2c3b372bb93af6f3ec5418f14751acaeca2c1dbf35

136 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1027 Obfuscated Files or Information

The PDF file contains embedded JavaScript, which is heavily obfuscated using eval() and unescape() functions. The ML classifier strongly indicates maliciousness. The presence of obfuscated JavaScript streams and the ML score suggest the PDF is designed to download and execute a secondary payload, although the exact mechanism and target are not fully discernible from the provided evidence. The extracted JavaScript files are named 'javascript_obj111611_000.js' and 'legacy_pdfkit_stage_000.js'.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
JavaScript action low PDF_JAVASCRIPT

PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
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.
String.fromCharCode low PDF_FROMCHARCODE

String.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)
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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj111611_000.js` `e7d1232c16a6e584ebcad6ed89ed39659361935894de0b1df6aee2e4fe16ce04`	pdf-javascript-stream	PDF /JS object 111611 at offset 0x7ED	478 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `3efc511cab3450d03e102f8bacbdfd90da7b688c05324fb0fdc497d6829faed9`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x189	2846 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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