Malicious PDF — malware analysis report

Static analysis result for SHA-256 7a71c79dabb3363b…

MALICIOUS

PDF

53.4 KB Created: 2017-11-13 00:19:47 +01:00
MD5: 085e31e1d46fa80fa787e63bb517b103 SHA-1: 9a0b0316eff206c4a17a46714040332de45e2600 SHA-256: 7a71c79dabb3363b138a463787368f8f6373607ddc174e30f2e8aeef7614e583
148 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

This PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The ML classifier also flagged it as malicious. The embedded JavaScript, named 'javascript_obj0001_000.js', is likely responsible for downloading and executing a second-stage payload, as suggested by the 'PDF_EMBEDDED_SCRIPT_PAYLOAD' heuristic. The specific nature of the payload could not be determined due to obfuscation.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9974

Heuristics 11

  • 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
  • Additional-actions dictionary low PDF_AA
    PDF defines /AA (Additional Actions) that references an executable action (JS/JavaScript/Launch/SubmitForm) — can auto-trigger on document or widget events. Form-field calc/format/validate/keystroke handlers in legitimate interactive forms commonly fire this, so it is reported as a low-weight signal; weaponised auto-execution is flagged by stronger rules (PDF_OPENACTION, encrypted-with-JS, etc.)
  • 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0029.bin
ddb2f0273ff53a78cba698afed0c23add8e219eaa85fecd99611493bebdb4d27		 pdf-embedded-file PDF EmbeddedFile object 29 at offset 0xC8DD 1237 bytes
javascript_obj0001_000.js
8c5efc6172b495c2941492d45b484300df1e4316f9bbd6a4d89e9505c54eaa72		 pdf-javascript-stream PDF /JS object 1 at offset 0x415 243 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
objstm_0035_00.bin
0c4066cdc4e3b10d19368102c6e368eb51409a1019c8764b8287ca938a7fcac5		 pdf-objstm-decoded PDF /ObjStm 35 0 obj (inflated) 1094 bytes

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