PDF malware analysis — malicious · 1c18d6b685b4b8de

MALICIOUS

PDF

15.8 KB

MD5: d8231c8a8b449d3bae959da98423c188 SHA-1: 55e9611b0251c483bb015e5148f1e56b747ebcd4 SHA-256: 1c18d6b685b4b8ded482f4d03aba51668d4ecdddc0016d5fd585b7885bb2a646

196 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File T1566.002 Spearphishing Attachment

The PDF contains embedded JavaScript that utilizes `eval()` and `String.fromCharCode()`, indicating obfuscated code execution. A high-confidence ML classifier and ClamAV detection (Pdf.Exploit.Agent-36086) confirm malicious intent. The primary attack pattern involves exploiting PDF vulnerabilities to run this script, which is likely a downloader for further malicious activity.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 7

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` `fec80f364af9bfde6f8617000aa94e7e5831ed943ee363100de1d43dacad4455`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	426132 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_off00003b91.bin` `6b603c8a3c336623b7e3e8102f3b49f240aac8f76779f5fed69056a549950c03`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x3B91	300 bytes

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