Malicious PDF — malware analysis report

Static analysis result for SHA-256 aa9cbfc31bb3885a…

MALICIOUS

PDF

52.7 KB Created: 2017-11-13 00:19:04 +01:00
MD5: b0db579d3218d8b56cdd3ba65138e1e1 SHA-1: eb728155ac53d371f429ff70017a3566da591539 SHA-256: aa9cbfc31bb3885a17fda04286b4bfb6581e4d2860551ebd3043e75a292ceaae
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1105 Ingress Tool Transfer

The PDF file contains embedded JavaScript, indicated by PDF_JAVASCRIPT and PDF_JS heuristics. High-confidence firings like PDF_EVAL and PDF_EMBEDDED_SCRIPT_PAYLOAD suggest the script is malicious and likely attempts to download and execute a second-stage payload. The ML classifier also strongly flagged this PDF as malicious. No specific family could be identified, but the technique of embedding obfuscated JavaScript for payload delivery is common.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9918

Heuristics 10

  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Embedded script payload in PDF stream medium 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.
  • 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)
  • AcroForm button with action trigger low PDF_ACROFORM_BUTTON
    PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures
  • 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://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://purl.org/dc/elements/1.1/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0029.bin
ddb2f0273ff53a78cba698afed0c23add8e219eaa85fecd99611493bebdb4d27		 pdf-embedded-file PDF EmbeddedFile object 29 at offset 0xC62D 1237 bytes
javascript_obj0001_000.js
fa64b4b18bae88a35a311c66e2da3b8e533af452982f59d90014b76eec69b141		 pdf-javascript-stream PDF /JS object 1 at offset 0x3EE 210 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).

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