Malicious PDF — malware analysis report

Static analysis result for SHA-256 51d7f3bccc75eb4f…

MALICIOUS

PDF

73.4 KB Created: 2021-04-07 11:04:57 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: d677c3f443eda38fc2632150139faad8 SHA-1: ef0ed9b2b8708872775e839885b91ada99c77292 SHA-256: 51d7f3bccc75eb4ff504416b0efd0ef8d7ce4e43e7824ede0f957d7ec5ec5731
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript

This PDF document, identified as malicious by ML classifiers and ClamAV, contains a large number of external links, suggesting it is part of a link farm or phishing campaign. The document body, though heavily obfuscated, appears to be related to educational content, likely a lure. The presence of numerous PDF links, including one pointing to 'vilenefex.ru', indicates an attempt to redirect users to potentially malicious websites for further exploitation.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • External URI info PDF_URI
    PDF contains an external URL action
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • 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 https://vilenefex.ru/123?utm_term=linear+equation+worksheet+algebra+2
    • https://cdn.sqhk.co/zowipitilo/RCrtg61/54296893949.pdf
    • https://cdn.sqhk.co/jakufomego/jejjhd8/relevant_experience_resume_template.pdf
    • http://selolatoxomida.22web.org/70021108347.pdf
    • https://cdn.sqhk.co/letijefa/oidXZ0H/centurylink_router_login.pdf
    • https://cdn.sqhk.co/nedupugifuka/0jdgfid/74364529962.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/7f3aeb39-ca02-468c-b1bf-5546e267653e/7010290303.pdf
    • https://486bfeb6-87d8-40a3-812f-3449909c9139.filesusr.com/ugd/81b904_2c8fe4154ae24c3686f4fba04fbeaf2a.pdf?index=true
    • https://33da92c3-26de-4f6b-bf12-1693cb6a6e79.filesusr.com/ugd/0307f2_182092b51ac44edcb0795e53e27ab537.pdf?index=true
    • https://d86ad34a-7df2-4f47-937b-a12ab5abc0fa.filesusr.com/ugd/8cbfce_60b9c5be88984c408c48aa712cc2e453.pdf?index=true
    • https://uploads.strikinglycdn.com/files/7fb5f8e2-555c-4e1e-a44c-c0d8f21bfbda/how_to_start_a_coleman_dual_fuel_stove.pdf
    • https://uploads.strikinglycdn.com/files/7a071091-4278-42ea-bf0e-f5e1b84e415f/83699827489.pdf
    • https://a54de82d-0003-4787-801b-d7ee719c780a.filesusr.com/ugd/8d57bd_06c2260498f24b5e860f5728a87c701d.pdf?index=true
    • https://0ac950e2-707a-4e47-8bf4-daface0ea9db.filesusr.com/ugd/356f11_c6f029b2dd8e44479914167a7a5329f7.pdf?index=true
    • https://uploads.strikinglycdn.com/files/1f4b8f4e-d153-4cbe-ae49-e70a0f210244/lepigoj.pdf
    • https://uploads.strikinglycdn.com/files/4bd3465e-25a7-4190-b905-d7f294bce82d/65771971632.pdf
    • https://ba10d46a-d7c1-43af-8542-f1a50f31aa8a.filesusr.com/ugd/4dded2_2f406e01b53c48c292eb6d4d788e0be5.pdf?index=true
    • http://donenufalu.rf.gd/patevopetejekajonate.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000dfaa.bin
20bc9c0674ab04299a3e7cb37cfbec12713905cf2114c67f442f613b22edb620		 pdf-font-stream PDF embedded font (sfnt) at offset 0xDFAA 5440 bytes
font_01_sfnt_off0000f248.bin
f8b7f1c9552a36de8e777b6f4420bb3154e13f456d7ea51daa623eda71163a06		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF248 10792 bytes

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