Nemucod PDF malware analysis — malicious · 42bfdbe7ab20e41a

MALICIOUS

PDF

138.6 KB Authoring application: PyPDF2

MD5: c3d38bc9e21f1a718af7730eedf9b3e3 SHA-1: 91021cbed97fd33dcbd52806224d1f9dcb6fdf1a SHA-256: 42bfdbe7ab20e41ad2fccba0815c50aa4fe62f4368c8eabde073b4c96b9d88fc

226 Risk Score

Malware Insights

Nemucod · confidence 95%

MITRE ATT&CK

T1059.001 PowerShell T1105 Ingress Tool Transfer

This PDF file was detected as malicious by ClamAV with the signature Txt.Downloader.Nemucod-6769573-0. Static analysis revealed embedded JavaScript streams, including one that uses an eval() call, indicating code execution. The ML classifier also flagged this PDF as highly malicious. The presence of JavaScript and the ClamAV detection strongly suggest this file acts as a downloader for a second-stage payload, consistent with the Nemucod family's behavior.

Machine Learning

Nyx PDF Classifier malicious score 0.9849

Heuristics 6

ClamAV: Txt.Downloader.Nemucod-6769573-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Txt.Downloader.Nemucod-6769573-0
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 medium 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.

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `1a4ad4aa4374e2f0646a94261896f20d6532a60691eaf566501339275ed74c83`	pdf-javascript-stream	PDF /JS object 6 at offset 0x554	17691 bytes
Detection ClamAV: Txt.Downloader.Nemucod-6769573-0 Obfuscation or payload: likely Carved artifact contains 48 eval/decoder/string-building token(s). Carved artifact contains 2 long hex-escaped blob(s).
`javascript_obj0006_001.js` `8a73bc6ca2475acccf9d1ba3a18e5b2896481c06e8488d61e572709cdc8fcac3`	pdf-javascript-stream	PDF /JS object 6 at offset 0x554	232 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long hex-escaped blob(s).
`javascript_obj0178_002.js` `6ec6509be655ad55d7f043dd30a57424b3e40e0dcc056cf0d9c53cf4255c07fb`	pdf-javascript-stream	PDF /JS object 178 at offset 0x12737	808 bytes

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