PDF malware analysis — malicious · 73c9a6e62bbbadeb

MALICIOUS

PDF

2.2 KB

MD5: d8ef565ebc3c11d2f4d671253838b6de SHA-1: b5cc4208ba69977e2f93388abfb8fd5a1841fc9f SHA-256: 73c9a6e62bbbadeb4752a4ed51c5ca293667aeec8b00e6fb3302fafa1a343cf8

298 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF file contains obfuscated JavaScript that utilizes eval() and unescape() functions to decode and execute shellcode. This shellcode is designed to download a second-stage payload from the URL http://fortuna4.info/ph/l.php?i=5. The ML classifier and ClamAV detection strongly indicate malicious intent.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 10

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: Pdf.Exploit.Agent-36082 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-36082
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
PDF JavaScript shellcode contains an embedded download URL high PDF_JS_SHELLCODE_DOWNLOAD_URL

Decoded PDF JavaScript shellcode contains a hardcoded http(s) URL stored as little-endian %uXXXX Unicode escapes. Reader exploit shellcode embeds the second-stage fetch URL this way and pulls it down with a urlmon/URLDownloadToFile-style download-and-execute (commodity downloader behaviour rather than a specific Acrobat CVE).
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. (matched inside decoded stream)
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://fortuna4.info/ph/l.php?i=5

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj111611_000.js` `772da696bdb365f3f1eb4ea6af881baad391be62f3591b19f2f9827fcc4c9b53`	pdf-javascript-stream	PDF /JS object 111611 at offset 0x7D7	479 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `07125613536ebd33c7c794abd0ef742d8dfda12050edc70fd4273344cb1857ed`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x189	2822 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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