PDF malware analysis — malicious · 72d8a7ffa12e40eb

MALICIOUS

PDF

9.3 KB

MD5: 634b2341932a4870f96d0e37e65fae70 SHA-1: d9bcc5e3b53bf7abc6f20f21c5411eb0aeb110a9 SHA-256: 72d8a7ffa12e40ebce0cf45612e098057443a11da0b616da3e6da1e5cc75a337

146 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF file utilizes XFA forms and embedded JavaScript. The JavaScript contains a function 'hx' that decodes a hex string by subtracting 43 from each character's ASCII value. This decoded string is then passed to 'eval()', indicating the execution of a second-stage payload. The ML classifier strongly flagged this PDF as malicious, and the presence of XFA scripting confirms a high likelihood of malicious intent.

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` `09752c8ad60c4a8d2d6793e6b56eedec9aa7c960091b0a3fb2776b3cfc8e9216`	pdf-embedded-file	PDF EmbeddedFile object 41 at offset 0x52	1165 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`deobfuscated.js` `cfc36da52badce718eb09d835acab38316c32ffbd6a4716a43a47a2e1bf5617d`	deobfuscated-js	PDF JavaScript deobfuscation pass	1410 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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