PDF malware analysis — malicious · 56ec3f1d5c14d728

MALICIOUS

PDF

115.4 KB Authoring application: PyPDF2

MD5: ad50db0ae308c0b71b77ed5b2da91fa6 SHA-1: d4a10a75673c3ae2f319dbb88515770e3e5e2385 SHA-256: 56ec3f1d5c14d728ec6d7b39c436bc220c1bf04e10df84d4f2db64a2492752dc

194 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF contains heavily obfuscated JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_EVAL. The ML classifier also flagged it as malicious. The ClamAV signature 'Txt.Downloader.Nemucod-6769957-0' and the presence of multiple extracted JavaScript files suggest this PDF acts as a downloader for further malicious content. The obfuscation and downloader behavior point to a common malware delivery pattern.

Machine Learning

Nyx PDF Classifier malicious score 0.9797

Heuristics 6

ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution
Suspicious extracted artifact high 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.
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.
AcroForm button with action trigger low PDF_ACROFORM_BUTTON

PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures

Extracted artifacts 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `51a70a7e526d42f672e765c344220a996973331d1b31016c09eb3f184a2921dc`	pdf-javascript-stream	PDF /JS object 5 at offset 0x36A	13573 bytes
Detection ClamAV: Txt.Downloader.Nemucod-6769957-0 Obfuscation or payload: likely Carved artifact contains 26 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `a742206ff8a7f81d57a45c9de155e75a6cd77f53a09674a5cafce1d107698bf7`	deobfuscated-js	split-join delimiter stripped JavaScript at offset 0x430	7183 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 8 shell/COM execution token(s). Carved artifact contains 27 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_001.js` `ebd65937e7e74e8726799b16405f6c142ded32b73e0c76dc04b1733b838fe1ed`	deobfuscated-js	split-join delimiter stripped JavaScript at offset 0x3BC	117981 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 26 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_002.js` `67760a812b8cea027c7a72448d69f1fbf2e1913634d6b2d712fb35e03345a788`	deobfuscated-js	split-join delimiter stripped JavaScript at offset 0x45E	111603 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 8 shell/COM execution token(s). Carved artifact contains 27 eval/decoder/string-building token(s).

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