PDF malware analysis — malicious · 66cbc6cebd155408

MALICIOUS

PDF

35.2 KB

MD5: 1447275a313d5555a4fb747bd6b542a1 SHA-1: 9bd91420fce43e1eb7b7c89a8b8c281a01d74fae SHA-256: 66cbc6cebd1554084d9f4f232a3e32669ac91812bcc03538003d964023cb50d8

194 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file contains embedded JavaScript that is heavily obfuscated using String.fromCharCode and concatenation. The script appears to be designed to download and execute a second-stage payload, as indicated by the 'PDF_JS_EXPLOIT_CLUSTER' heuristic and the presence of an embedded SWF file. The benign URLs extracted are likely decoys or related to the XFA form functionality, not directly indicative of malicious C2.

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.
RichMedia (Flash) high PDF_RICHMEDIA

PDF contains /RichMedia (Adobe Flash) which is a historic exploit vector
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.
Embedded file low PDF_EMBEDDED

PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
XFA form low PDF_XFA

PDF uses XML Forms Architecture — can contain script logic
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://ns.adobe.com/xdp/
- http://www.xfa.org/schema/xci/2.6/
- http://www.xfa.org/schema/xfa-template/2.6/

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`Adobe.swf` `8f9c84c8c00bc62ae296a81fac6640aa852ea67548abc1bd639aa0da1a1696c4`	pdf-embedded-file	PDF EmbeddedFile object 16 at offset 0xE1B	27347 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.
`javascript_obj0006_000.js` `6f4256b48c20ab2ab6f8922872a17fd314ff29c6e47990f3224b32068d605535`	pdf-javascript-stream	PDF /JS object 6 at offset 0x105	10476 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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