Malicious PDF — malware analysis report

Static analysis result for SHA-256 a79bcf4d765cc087…

MALICIOUS

PDF

82.7 KB Created: 2021-09-12 12:04:23 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 2e4cd61b6edd46abb60b98192cf46f10 SHA-1: 61bda397d4f7db2734b6c78186720238e2a17199 SHA-256: a79bcf4d765cc087a328e981406c141cfdcdb896f5d31b20d1c014fc1e7a9893
176 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF contains numerous external links, many pointing to potentially compromised WordPress sites or disposable domains, suggesting a link farm designed to distribute further malicious content. The ClamAV detection and ML classifier strongly indicate malicious intent, likely phishing or malware delivery. The document body is heavily obfuscated and appears to be non-readable content generated by wkhtmltopdf, providing no direct user-facing lure.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9974

Heuristics 7

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • Clickable URI points to raw IP address medium PDF_URI_IP_LITERAL
    PDF contains a clickable HTTP(S) action whose host is a literal IPv4 address. Legitimate documents normally link to named domains; raw-IP destinations are common in disposable phishing and malware-delivery infrastructure.
  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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://www.majorisinvestimentos.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/16137d93c32a53---naninoj.pdf In PDF document text
    • http://geometracosentino.com/userfiles/files/39553501723.pdfIn PDF document text
    • http://157.230.241.115/image/upload/File/kosujogajaz.pdfPDF link annotation
    • http://373113.linker.tw/files/kudux.pdfIn PDF document text
    • http://dunakeszi.varosom.hu/userfiles/files/19266991641.pdfIn PDF document text
    • http://slowjamsundays.com/wp-content/plugins/formcraft/file-upload/server/content/files/16132649fc508e---finominuvaratutefose.pdfIn PDF document text
    • http://www.autoservis-hubatka.cz/admin/upload/ww/file/fafawobora.pdfIn PDF document text
    • http://mallenmediations.com/mallenmediations/images/userfiles/file/wojub.pdfIn PDF document text
    • https://kaimano.it/file/34622418068.pdfIn PDF document text
    • http://vatlieulamnha.com/media/ftp/file/44684869230.pdfIn PDF document text
    • http://girc.ncue.edu.tw/ckfinder/ckfiles/files/71370559677.pdfIn PDF document text
    • https://posetili.ru/userfiles/file/94931672152.pdfIn PDF document text
    • http://www.iycadana.org/wp-content/plugins/super-forms/uploads/php/files/79rq91gfe749krsatm5b5e5q02/76818199374.pdfIn PDF document text
    • https://dbmotorbrokers.com/userfiles/file/muvadijajerodop.pdfIn PDF document text
    • https://alpasol.e-giant.net/upload/files/dizanujawilovojububozu.pdfIn PDF document text
    • http://jingyitech.com/uploadfile/zitad.pdfIn PDF document text
    • http://architettorobertafasola.eu/userfiles/files/natuzejununawakivewiwa.pdfIn PDF document text
    • http://sofia-es.tokyo/yamituki-n/uploads/files/31414861963.pdfIn PDF document text
    • http://kocavietnam.com/upload/files/90190012207.pdfIn PDF document text
    • https://valleyrentals.com/userfiles/file/kukotuvaro.pdfIn PDF document text
    • http://www.hotel-margherita.com/wp-content/plugins/formcraft/file-upload/server/content/files/16137b68bd4e8a---89857436476.pdfIn PDF document text
    • http://lichnyiybrand.ru/wp-content/plugins/formcraft/file-upload/server/content/files/16138273a3a944---tukedogikove.pdfIn PDF document text
    • http://facyt.com.ar/ckfinder/userfiles/files/83568157453.pdfIn PDF document text
    • http://feldbach-tourismus.at/files/jupuvisuwij.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/1xuhb7AK25c/uplcv?utm_term=grimorium+verum+peterson+pdfPDF 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_off0000d928.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD928 19200 bytes
SHA-256: 85010659540d9eb32957d24c6e4a6ccd71d19b4b33bd4fcbf856f9056d299df7
font_01_sfnt_off00010b33.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10B33 10656 bytes
SHA-256: a25a698a8b2cbfa3a8c98ddbb29acddf63b9f7efd753b9626bbd7622ba554306
font_02_sfnt_off000123a4.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x123A4 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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