Malicious PDF — malware analysis report

Static analysis result for SHA-256 7a550cb971275289…

MALICIOUS

PDF

29.8 KB
MD5: 6a6be42fbe1dba8b2b185b7b9f803dc8 SHA-1: 3c05be4fbe485fe5c813ad3f666295e698f7f0aa SHA-256: 7a550cb97127528946498f713c50dd3fab0e86a73c1351f46cab328729b88285
174 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

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 from one of the provided URLs. The presence of PDF JavaScript exploit cluster heuristics and ML classification strongly indicates malicious intent. The embedded SWF file may also be part of the exploit chain.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 9

  • 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
  • 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://code.flashdynamix.com/AES/aes-decrypt.php
    • http://code.flashdynamix.com/AES/aes-encrypt.php
    • http://ns.adobe.com/xdp/
    • http://www.xfa.org/schema/xci/2.6/
    • http://www.xfa.org/schema/xfa-template/2.6/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#
    • http://adobe.com/AS3/2006/builtin

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
test.swf
4d4d42d908c48737d0cbe1f33c14f197803950e6ff47f9c0f13e1d51a231494d		 pdf-embedded-file PDF EmbeddedFile object 16 at offset 0x8CC 53991 bytes
javascript_obj0006_000.js
4396c97f8ac414e3b7cec10e6d1d75f11bef3161a64c96c2847568631d03c8af		 pdf-javascript-stream PDF /JS object 6 at offset 0x106 11498 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 239 eval/decoder/string-building token(s).

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