PDF malware analysis — malicious · 622bfa56a2afa2ac

MALICIOUS

PDF

118.5 KB

MD5: 8109e3e92deaa69d4b5a726e301867bb SHA-1: fe84a4b4045310d668b3983cf4c7345f5e670051 SHA-256: 622bfa56a2afa2ac072a3a500f0522ccb02fc285647b9085cc8bca74a562162d

256 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file contains obfuscated JavaScript that utilizes eval() and String.fromCharCode() to execute malicious code. The critical PDF_JS_EXPLOIT_CLUSTER heuristic firing, along with ML and ClamAV detections, strongly indicates an exploit. The JavaScript is designed to download and execute a second-stage payload, as suggested by the 'eval stager' heuristic.

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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `044596a782dfee38a16fe34f86602299470da76fc5cdcc1b2faab319cc828238`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627250 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_off0001d6ab.bin` `927f1682912473141cb569b5db86c9ba04e21f6050b6657f0d1a4cd9d732e414`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x1D6AB	300 bytes
`stream_002_off0001d85e.bin` `822ba5949db2f82f6b83dcc5f3a30faa60c0f4b8e33b448b97f717468ae2a6c0`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x1D85E	200 bytes

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