Nemucod PDF malware analysis — malicious · a0bb4728c53edece

MALICIOUS

PDF

89.7 KB Authoring application: PyPDF2

MD5: a64ccb02bd204b04c5bee67ea3072399 SHA-1: 24d3b3b53d33dc4ab90a693622b74a716341c702 SHA-256: a0bb4728c53edece3df2d3ea20ea4af28901a734d777ca99a753a4c3d24afe70

226 Risk Score

Malware Insights

Nemucod · confidence 95%

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF contains embedded JavaScript, flagged by multiple heuristics including PDF_JAVASCRIPT, PDF_JS, and PDF_EVAL. The ML classifier and ClamAV detection strongly indicate maliciousness, identifying the family as Nemucod. The embedded JavaScript is likely responsible for downloading and executing a secondary payload, as suggested by the 'Txt.Downloader' ClamAV signature. The document body is heavily obfuscated and unreadable, providing no direct clues to the lure.

Machine Learning

Nyx PDF Classifier malicious score 0.9993

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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0004_000.js` `4d5ac984f32ce66138c7a1a642e1f5dd5b51ddb24b968698f8616149fb5e491d`	pdf-javascript-stream	PDF /JS object 4 at offset 0x12F	17440 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_obj0004_001.js` `d473f30b23b5a714a466ba833edd4cc385e808220cd4dfb6750e60316e3cc0c8`	pdf-javascript-stream	PDF /JS object 4 at offset 0x12F	233 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).

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