Txt.Downloader.Nemucod-6769573-0 PDF malware analysis — malicious · 05b516fe27ec0221

MALICIOUS

PDF

59.2 KB Authoring application: PyPDF2

MD5: e98802f1510ee971bc230ff6022bfbe1 SHA-1: 6aaf105a351272109d803576d5bccf79e939091f SHA-256: 05b516fe27ec02210829b8d1ba762de829eaa12c5b584626867841bc15507759

286 Risk Score

Malware Insights

Txt.Downloader.Nemucod-6769573-0 · confidence 95%

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF file was detected as malicious by ClamAV and ML classifiers, indicating it contains a downloader. The embedded JavaScript, obfuscated using hex escapes and eval(), is designed to execute and likely download a secondary payload. The primary technique observed is the exploitation of PDF vulnerabilities to run JavaScript, which is then used to fetch further malicious content.

Machine Learning

Nyx PDF Classifier malicious score 0.9982

Heuristics 7

PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER

PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
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_obj0008_000.js` `a1130cb1e5490d6ce4962bed5982d78c81b0683ff18d65bfbce4b82804da6b09`	pdf-javascript-stream	PDF /JS object 8 at offset 0x69A	17469 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_obj0008_001.js` `43e5972dbc06a39d481d4212f1ac66b2469984e12be3003b7fa9f8132c8aa43c`	pdf-javascript-stream	PDF /JS object 8 at offset 0x69A	737 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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