Malicious PDF — malware analysis report

Static analysis result for SHA-256 b931303a5af85535…

MALICIOUS

PDF

77.6 KB Created: 2021-04-04 09:25:18 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-22
MD5: db9b7e3986ddf0f9afd9fea0989cdf2b SHA-1: 2df3ea8f6f908855f992c0173e3d07d7b2066902 SHA-256: b931303a5af85535f653c2eb54cfb6106cca39fd5f914532ea71f16aacc7983c
126 Risk Score

Malware Insights

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

The file is identified as malicious by ClamAV and an ML classifier, with multiple heuristics indicating it's a link farm on disposable hosting. The embedded URLs, such as 'https://resalured.ru/strik?utm_term=how+to+start+think+smart+pdf', likely lead to phishing or malware download sites. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create malicious PDFs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://resalured.ru/strik?utm_term=how+to+start+think+smart+pdf PDF link annotation
    • https://cdn-cms.f-static.net/uploads/4449968/normal_6052cacef2da2.pdfIn PDF document text
    • http://pogawubujogeje.mypressonline.com/comment_regrouper_plusieurs_pages_en_un_seul_document.pdfIn PDF document text
    • https://cdn.sqhk.co/jadizefon/ifJriff/33401375332.pdfIn PDF document text
    • https://cdn.sqhk.co/wogebebaruro/egcTvEA/strategy_project_manager.pdfIn PDF document text
    • http://gaximivotekole.mypressonline.com/bizawel.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4470523/normal_5ffbf5ce32de1.pdfIn PDF document text
    • https://cdn.sqhk.co/kojariwirip/cgfngiH/love_stories_movies_2020.pdfIn PDF document text
    • https://cdn.sqhk.co/mujejadalale/JgiQtgh/lineage_blade_dancer_guide.pdfIn PDF document text
    • http://pixujuxe.mypressonline.com/abdellah_nursing_theory.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4465400/normal_6057d99a757e6.pdfIn PDF document text
    • http://wozupabalaviv.medianewsonline.com/xbox_one_controller_bluetooth_adapter_for_headphones.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://uploads.strikinglycdn.com/files/963811c1-3d66-4371-9a12-7ae6f86c17d3/43301490913.pdfIn PDF document text
    • http://jujobope.atwebpages.com/91609304198.pdfIn PDF document text
    • http://limoxukuk.atwebpages.com/rivesumulometidotitej.pdfIn PDF document text
    • http://sizikukot.epizy.com/dream_high_ost.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/cf291af7-3a1b-4ac0-929c-0ee0d03fe8db/just_mercy_book_club_questions.pdfIn PDF document text
    • http://dijejewilibafux.onlinewebshop.net/biology_grade_12_textbook.pdfIn PDF document text
    • http://zatupux.rf.gd/3154048578.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/c12b8b02-43b8-49c0-b4e7-961dcf67abf3/64503162169.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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000f18b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF18B 5368 bytes
SHA-256: 6d8e39bc428d82452dcd33ed4ad245528131a1cea448efaab54af7167a4abf3a
font_01_sfnt_off000103af.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x103AF 10984 bytes
SHA-256: bc0530b8021a15119ef4079bb244cd6ec30429063dd36fbe03e95bc36ad7cbec

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