PDF malware analysis — malicious · 728e621379437313

MALICIOUS

PDF

2.2 KB

MD5: a16863d435c3be9b2543b50683cb15ee SHA-1: 3feae89a27b664bc2118fd2cf0f69713a4628aa3 SHA-256: 728e621379437313c34670beec6b9937341790c2e3573ffc499b37b14c852199

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 embedded URL http://vidostore.info/new_aaa/l.php?i=5. The presence of exploit cluster heuristics and ClamAV detection confirms the malicious nature of the file.

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://vidostore.info/new_aaa/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 0x7E5	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` `dd20b40ae32ef830e9ee7cfe3ccbfceb3898783e59eb6b3cabb155d39faaa0db`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x189	2840 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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