Malicious PDF — malware analysis report

Static analysis result for SHA-256 637539a6782ac8f2…

MALICIOUS

PDF

100.6 KB Created: 2021-09-10 03:23:21 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-09-29
MD5: e4fb2b5f9aa63d177003a9c17bc4dd32 SHA-1: 8f4e947c8bf3b0c417f252bcaf98b2bc0fc7c314 SHA-256: 637539a6782ac8f2e0613ed1984e70fe0f5506346eeff8b4d4c3a9dce72c7acf
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF file flagged by ClamAV as Pdf.Phishing.Trojan and by an ML classifier as malicious. It contains numerous embedded URLs that point to various domains, suggesting it is part of a link farm designed to redirect users to potentially malicious websites. The presence of PDF_SEO_DISPOSABLE_LINK_FARM heuristic further supports this, indicating a strategy of using many distinct, disposable hosts for redirection.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9989

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • Small PDF is a non-clustered link farm on disposable hosting medium PDF_SEO_DISPOSABLE_LINK_FARM
    Small PDF contains many clickable external PDF links spread thin across many distinct hosts (no single dominant host), corroborated by a utm_term SEO-redirector link and/or links parked on free/disposable content hosts. This is the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains, rather than a normal document citation pattern. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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://inwebjor.ru/uplcv?utm_term=walking+dead+season+10+episode+19+online+free PDF link annotation
    • https://maymac.info/userfiles/file/71670612396.pdfIn PDF document text
    • http://emailreceptionist.net/userfiles/file/80216497874.pdfIn PDF document text
    • https://evermoral.hk/upload/file/1630525762.pdfIn PDF document text
    • http://newbiesites.com/userfiles/file/vidawaxawomi.pdfIn PDF document text
    • https://www.hmgfinance.com/ckfinder/userfiles/files/pavojokadiwude.pdfIn PDF document text
    • http://parentini.it/userfiles/files/xewuxu.pdfIn PDF document text
    • https://kottayammedicalcollege.org/CMS/ckfinder/userfiles/files/77745556241.pdfIn PDF document text
    • http://p-energo.ru/content/file/pujagema.pdfIn PDF document text
    • https://tolgyesvolgy.hu/userfiles/file/576686449.pdfIn PDF document text
    • http://etalentlink.com/uploadfile/file///2021090501513520.pdfIn PDF document text
    • http://canshu.dlzj.net/upload/files/20210910031013702670.pdfIn PDF document text
    • https://pbpkrosno.com/fckfile/46718985948.pdfIn PDF document text
    • http://z500.si/files/nirovopumuwoxalijuxupofos.pdfIn PDF document text
    • http://www.tiande-global.com/ckfinder/userfiles/files/fobodewogekunaregijuzad.pdfIn PDF document text
    • http://bigdoughpizza.com/uploads/files/dewuk.pdfIn PDF document text
    • https://mcq-exambd.bdbabymart.com/app/webroot/ckfinder/userfiles/files/zozekijevitafiku.pdfIn PDF document text
    • http://tgtech-auto.com/userfiles/file/gokufurajalodufolitotawuj.pdfIn PDF document text
    • http://bannhuaduong.net/upload/files/moxuvoro.pdfIn PDF document text
    • http://jtravel.clickis.kr/FileData/ckfinder/files/20210908_2FAEDA3A13BD5269.pdfIn PDF document text
    • http://seychelles-resort.com/images/blog/file/10366195571.pdfIn PDF document text
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off00012354.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12354 18300 bytes
SHA-256: 365958b765115b36cf2506d13f24f226c5638398cbb450092f8b77c17f945c1a
font_01_sfnt_off000152eb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x152EB 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00016b02.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x16B02 11000 bytes
SHA-256: 7b785120d22da57ba2002950a9af5771be4f68966a28fd1248481b0ed64b4bdb

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