Malicious PDF — malware analysis report

Static analysis result for SHA-256 23fb941f3c393df1…

MALICIOUS

PDF

70.1 KB Created: 2021-11-14 05:35:20 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-25
MD5: 5cf0ffe986d7c2a3d33338e4e2c615bc SHA-1: ad8b3bb5a269d1ffd1bd724df4d5d53e6617303d SHA-256: 23fb941f3c393df133f39bfbe767688d0a0a83477fa605d8aa27e991f864229e
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file is a PDF identified as malicious by ML classifiers and ClamAV. It contains numerous embedded URLs, many pointing to PDF files on various domains, suggesting a link farm or content distribution network. One heuristic specifically flags it as a 'PDF_SEO_DISPOSABLE_LINK_FARM', indicating a non-clustered link farm on disposable hosting. While no scripts were explicitly extracted, the PDF structure and embedded URIs are indicative of an attempt to manipulate search results or redirect users to potentially malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9992

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 http://okuninka-biale.pl/userfiles/file/sejajusipiwesarodupe.pdf In PDF document text
    • https://gitteszoneklinik.dk/ckfinder/userfiles/files/1886874249.pdfIn PDF document text
    • http://topup-fight.com/ckfinder/userfiles/files/92728562404.pdfIn PDF document text
    • http://www.kinoimaging.nl/wp-content/plugins/formcraft/file-upload/server/content/files/16152c9bfd6990---71439562751.pdfIn PDF document text
    • https://idosekotthonaveresegyhaz.hu/files/files/66367987224.pdfIn PDF document text
    • https://www.borzabadi.com/ckfinder/userfiles/files/nobudezoloritezumakamamul.pdfIn PDF document text
    • http://shceping.com/upFile/photos/2021-10/file/8210912033.pdfIn PDF document text
    • http://powercleanperu.com/cms_powerclean_2015/sgi_userfiles/userfiles/files/supaxivurasaguwodato.pdfIn PDF document text
    • http://radyoislam.com/resimler/files/kulezig.pdfIn PDF document text
    • http://bebsulmare.com/userfiles/files/zemefurado.pdfIn PDF document text
    • https://karatenarrewarren.com.au/ckfinder/userfiles/files/16187174471.pdfIn PDF document text
    • http://newbiiz.com/upfiles/file/90145099375.pdfIn PDF document text
    • https://www.fifatravels.com/wp-content/plugins/formcraft/file-upload/server/content/files/1616702bbdc5f5---watukugux.pdfIn PDF document text
    • http://area100impianti.it/userfiles/files/kirirob.pdfIn PDF document text
    • http://stefanourso.com/public/userfiles/file/dekepigil.pdfIn PDF document text
    • https://strategieb2b.ca/userfiles/file/powewofajemufaleli.pdfIn PDF document text
    • http://debseven.net/UserFiles/File/kitabagusose.pdfIn PDF document text
    • http://architects-desk.com/uploadsfile/mufel.pdfIn PDF document text
    • http://feedproxy.google.com/~r/Xvkpad/~3/1hHberoKktI/uplcv?utm_term=elephant+coloring+pagesPDF link annotation
    • 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_off0000ac88.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xAC88 17652 bytes
SHA-256: f1b8f3c8877668a3be30bfc61e0feb4c6c4cc79b1089a85fa4bd3fb27c1c2b3c
font_01_sfnt_off0000da3d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDA3D 10636 bytes
SHA-256: f2e45040f7b78f23c90530c1534746a802cea83f3b36bc20142ff8d9a7024514
font_02_sfnt_off0000f280.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF280 16540 bytes
SHA-256: 45015263e28dbf00792e0fa83ae0fb9123af5110209f191c00797c49350166ef

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