PDF malware analysis — malicious · 735aad3455a08d5d

MALICIOUS

PDF

9.5 KB

MD5: 0f1a8ac81e6df1b8fcb3e65aff2f3447 SHA-1: 39492d4870caef9497058171082410cc40da0d38 SHA-256: 735aad3455a08d5d0f57f98170d43efc7038f990d45b1f6fd63fe8c0c6b6bbe6

146 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF file contains an XFA form with embedded JavaScript. This script uses a custom decoding function 'hx' to deobfuscate a string from the 'subject' property, which is then executed via eval(). The deobfuscated string likely represents a second-stage payload. The presence of XFA, embedded scripts, and the use of eval() strongly indicate malicious intent, likely for downloading and executing further malware.

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` `ceb156ae276f335e179f690f9142d2715e5ab593ce2ad613d87e950c8cd3206f`	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` `a6426d09c15aeb908d97d6015c88f8b1bd823a0980dd5afe2b7f49694103b7c4`	deobfuscated-js	PDF JavaScript deobfuscation pass	1933 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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