PDF malware analysis — malicious · 5f22ea8561454602

MALICIOUS

PDF

21.2 KB Authoring application: Nitro PDF Professional 6

MD5: 886152bc919fa70d9ed832f5afb0abe4 SHA-1: c46b3a9c535ee09521d4503cfef7e946ac4a6ddb SHA-256: 5f22ea8561454602ca4c6979a9950b46aa5ff3fbcbbd1f6b8d8d98121ad7be17

158 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF contains embedded JavaScript that utilizes eval() and String.fromCharCode() for obfuscation, a common technique for executing malicious code. The script is designed to download and execute a second-stage payload, as indicated by the PDF_JS_EXPLOIT_CLUSTER heuristic. While the specific payload URL is obfuscated within the script, the presence of this exploit cluster and the ML classifier's high confidence score strongly suggest malicious intent.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

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.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (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.
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.
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://crl.microsoft.com/pki/crl/products/CSPCA.crl0H
- http://www.microsoft.com/pki/certs/CSPCA.crt0
- http://crl.microsoft.com/pki/crl/products/tspca.crl0H
- http://www.microsoft.com/pki/certs/tspca.crt0
- http://www.microsoft.com/typography

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0001_000.js` `3a84724791c393e14e67b3126fa56ae28a823d918609052a27a469720f833ffc`	pdf-javascript-stream	PDF /JS object 1 at offset 0x10	3871 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`font_00_sfnt_off00001830.bin` `a1802d05cded6db969b5d5215e40b113fc076adb6f5029825e543a9338a14fb0`	pdf-font-stream	PDF embedded font (sfnt) at offset 0x1830	16160 bytes

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