PDF malware analysis — malicious · 664b8781aa9c999b

MALICIOUS

PDF

9.5 KB

MD5: ccd4fecc20a5ad95ecd46f8f9bb0b498 SHA-1: 0d040e1fcd01fb73a336ad7d1edae9327ded052c SHA-256: 664b8781aa9c999bd67b2bdb5a9748ea4626b0eedfae1c294fadd1d4070da5a4

146 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file utilizes XFA forms and embedded JavaScript to achieve code execution. The JavaScript function 'hx' decodes a hex-encoded string from the 'subject' property and then executes it using 'eval()'. This mechanism is designed to download and execute a second-stage payload, as indicated by the ML classifier and heuristic firings.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 8

XFA form contains risky executable script high CVE related PDF_XFA_SCRIPT

PDF embeds an XFA form whose script block contains exploit, submission/launch, or shell-execution primitives. Ordinary LiveCycle print/update scripts are left as generic XFA/JS signals unless stronger behavior is present.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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)
Embedded script payload in PDF stream low PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
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/1.0/
- http://www.xfa.org/schema/xfa-template/2.4/
- http://www.xfa.org/schema/xfa-data/1.0/

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`embedded_file_obj0041.bin` `41603e552f75398b847ad3bfedf08f54635fa61ab473793628a7de2fb1dc892b`	pdf-embedded-file	PDF EmbeddedFile object 41 at offset 0x52	1163 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`deobfuscated.js` `25b7ef793306cb47418c6f67b0ad6978d85c125d673691909ada02b0e73d2685`	deobfuscated-js	PDF JavaScript deobfuscation pass	1620 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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