PDF malware analysis — malicious · 038b565d663403b7

MALICIOUS

PDF

22.9 KB

MD5: 3245c90388e0e1e74b72e77c8a76611f SHA-1: 9ee72a7797bb9151335d0a6b3a0c45bf4e189d28 SHA-256: 038b565d663403b7e8027507bf91c68245586ffa1374a0c0579774ab3467b6ed

184 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1566.001 Spearphishing Attachment T1140 Deobfuscate/Decode Files or Information

The PDF contains embedded JavaScript that utilizes `unescape` and `String.fromCharCode` for obfuscation, indicating an attempt to hide malicious code. The script attempts to evaluate a string derived from `this.subject`, which is likely a URL or command. This pattern suggests the PDF is designed to act as a downloader for a second-stage payload, commonly delivered via spearphishing.

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.
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX

Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
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)
ASCII85Decode filter (with exploit indicators) low PDF_FILTER_85

ASCII85 encoding filter present alongside exploit delivery indicators — uncommon outside of obfuscation
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj3332_000.js` `cb9b9d25fac45af8acf5581013b50b83ff981546116f35d9f693d8edc7b732ff`	pdf-javascript-stream	PDF /JS object 3332 at offset 0x584F	482 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).

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