Malicious PDF — malware analysis report

Static analysis result for SHA-256 c88a7b7a33598bf7…

MALICIOUS

PDF

74.2 KB Created: 2021-06-22 10:46:01 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-07
MD5: 19ea8688d088845bb55e1c7671c9a2f9 SHA-1: a58ab9c1bb815af09f89884048a36b9e215dd05a SHA-256: c88a7b7a33598bf7adf00a857df2c7e441fb8e650a2671ae324ff34432289881
156 Risk Score

Malware Insights

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

The PDF was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, directing users to multiple compromised WordPress upload sites and other unknown domains. The document body, though heavily truncated, contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create PDFs from web content, further supporting the link farm hypothesis.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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 https://tcufroghouses.com/wp-content/plugins/formcraft/file-upload/server/content/files/160c00f4c8acaf---rinowevavulubam.pdf In PDF document text
    • https://myphi.biz/nbloom/fckuploads/file/zelopave.pdfIn PDF document text
    • http://josephlillianmorrisfamily.com/clients/59960/File/wejetitudajimomikikepeg.pdfIn PDF document text
    • http://www.theagentpipeline.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608e92659d220---21989545177.pdfIn PDF document text
    • https://suhrsmad.dk/wp-content/plugins/formcraft/file-upload/server/content/files/1607651d99bf1d---moboguvavagakori.pdfIn PDF document text
    • https://vsetinrally.cz/userfiles/file/mokagoketaw.pdfIn PDF document text
    • http://primebrokeragetx.com/ckfinder/userfiles/files/29863664121.pdfIn PDF document text
    • http://fouladsazanco.com/Upload/file/57620508661.pdfIn PDF document text
    • http://lilit-realty.com/wp-content/plugins/super-forms/uploads/php/files/cuapv67qoo1leilciu2dgt2421/zaxetaranakixibeke.pdfIn PDF document text
    • http://almar-bus.pl/userfiles/file/6697092384.pdfIn PDF document text
    • http://matstravel.ru/userfiles/file/22533400704.pdfIn PDF document text
    • https://ajwatravel.com/wheelmarine/userfiles/file/38963458898.pdfIn PDF document text
    • https://hotnews.md/upload/userfiles/files/92128160517.pdfIn PDF document text
    • http://irmascaritasdejesus.org.br/wp-content/plugins/formcraft/file-upload/server/content/files/1609c9242672e8---renowutezumelobefu.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/S30rS-6n6vg/uplcv?utm_term=must+read+haruki+murakami+booksPDF 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e599.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE599 5244 bytes
SHA-256: 7420b6e0b401ccf9f4ae7484268f187c904f5a678b288b74c23afd1eccd76219
font_01_sfnt_off0000f749.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF749 10892 bytes
SHA-256: 5bc8accadebc0885d17c12327a8bcae9943a7d70549084753b600f1879e22ce1

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