PDF malware analysis — malicious · 72d16c86bbff9592

MALICIOUS

PDF

15.7 KB

MD5: 83d2460235315febb7574b09046f0cca SHA-1: 709c73e9489d8b8213fa4f9f91cfedb93714f383 SHA-256: 72d16c86bbff959211a59e5600195ea707853bbd2e2e0493fa89c13cf9d43eef

256 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1059.007 JavaScript

The sample is a PDF file that contains embedded JavaScript. Heuristics indicate the JavaScript uses eval() and String.fromCharCode, common techniques for obfuscation and exploit execution. The ML classifier and ClamAV detection strongly suggest malicious intent, likely involving the exploitation of a PDF vulnerability to run a malicious script. This script is presumed to download and execute a secondary payload, as indicated by the PDF JavaScript exploit cluster firing.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 8

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-36086 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL

PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `f5caa5282a7c9f8993088b96f9af691a7be8ece966cc609fdedf8824a403737c`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	424408 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).
`stream_001_off00003b56.bin` `6971c7f38b6293b2cada050b3057beaa4120bf252c8392325caf7cfa5bf6994a`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x3B56	300 bytes

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