PDF malware analysis — malicious · 04b49d00510cfa27

MALICIOUS

PDF

15.4 KB

MD5: 71a456cc5c3a66bc808b64f6d18e4986 SHA-1: 96647cef7f79920bf0d49cf6226974a26c4643e5 SHA-256: 04b49d00510cfa2718a635da26a5728a2386f36f145b81d45e6f636bab89a2d0

226 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF contains embedded JavaScript that uses eval() and unescape() functions, indicating an attempt to obfuscate malicious code. The script iterates through a string 'hydo', applying a character code subtraction based on the number of pages in the PDF. This process reconstructs a function name which is then called with a parameter derived from the PDF's info dictionary. This behavior strongly suggests the script is designed to download and execute a secondary payload, likely exploiting a known PDF vulnerability.

Machine Learning

Nyx PDF Classifier malicious score 0.9997

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.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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.
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0012_000.js` `09de78b7de291aa3ddc78e96475725267630bf326894c1fb6b9aff709f8aec31`	pdf-javascript-stream	PDF /JS object 12 at offset 0x1BF2	363 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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