Malicious PDF — malware analysis report

Static analysis result for SHA-256 3b9944bbb3d1e088…

MALICIOUS

PDF

46.9 KB
MD5: 95db59af36472f8e450c38a1441eb3a4 SHA-1: 314fb2482ad3f8d62bf5b72a34be3a7f74866a2e SHA-256: 3b9944bbb3d1e088c03882d2d5cde19bcd2ac4059aa5d002d9165674a1617fea
156 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1566.002 Spearphishing Attachment

This PDF file was flagged as malicious by ClamAV and a machine learning classifier. It contains an embedded JavaScript stream which is likely responsible for exploiting a vulnerability, potentially CVE-2018-4990, to download and execute a second-stage payload from the external URI http://unique.bx2dscvppabfcpssiewlvwnknp8ppnnp.top/250920170000006734569912369086500998.pdf. The presence of active content and embedded files points towards a dropper or exploit delivery mechanism.

Machine Learning

  • Nyx PDF Classifier malicious score 0.7637

Heuristics 7

  • JPXDecode + active content — JPEG2000 CVE-family indicator high CVE related PDF_JPX_CVE_2018_4990_RELATED
    PDF uses /JPXDecode (JPEG2000) alongside JavaScript, XFA, or RichMedia indicators. This matches the delivery pattern for Adobe Reader JPEG2000 parser exploit families, including CVE-2018-4990, but does not prove the exact malformed JP2/JPX primitive.
  • ClamAV: Pdf.Dropper.Agent-7251403-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Dropper.Agent-7251403-0
  • 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. (matched inside decoded stream)
  • 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. (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 (matched inside decoded stream)
  • External URI info PDF_URI
    PDF contains an external URL action
  • 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://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/pdf/1.3/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_002_off00000445.js
f4f27d050fdec2de05005217f5e7c723f561ad64b3c582274783debf3c4c383b		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x445 16888 bytes

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