Malicious PDF — malware analysis report

Static analysis result for SHA-256 3b8c1535bb460cdb…

MALICIOUS

PDF

71.6 KB Created: 2021-02-20 08:19:24 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: 407199bd8ceb4e667ab4c669214c0602 SHA-1: 8e3d8d53327f801b183e4764a28d045eeb38e490 SHA-256: 3b8c1535bb460cdb581a6ffc164a86d33ad23d6535d3d263dc8595f766aef025
126 Risk Score

Malware Insights

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

The sample is a PDF document that contains numerous embedded URLs, many of which point to disposable hosting. The heuristic PDF_SEO_DISPOSABLE_LINK_FARM indicates a link farm strategy, and the ML classifier and ClamAV detection strongly suggest malicious intent. The document body, though heavily obfuscated, appears to be a lure related to educational content, likely to trick users into visiting the malicious URLs.

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://seumenha.ru/wix?keyword=solving+exponential+and+logarithmic+functions+worksheet PDF link annotation
    • https://cdn-cms.f-static.net/uploads/4477873/normal_601079c9ce86a.pdfIn PDF document text
    • http://jatuligirez.22web.org/what_liquor_goes_with_kahlua.pdfIn PDF document text
    • https://cdn.sqhk.co/xusawikorut/lVhfc2F/98747663525.pdfIn PDF document text
    • http://fixegemixinazoj.22web.org/sartorius_muscle_stretches.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4475866/normal_5ff5edeeaf03c.pdfIn PDF document text
    • http://nejoxulogawa.22web.org/vevuminagejaginunekevimuv.pdfIn PDF document text
    • https://cdn.sqhk.co/depifozopupe/ihAjagi/avatar_maker_fantasy_chibi_doll.pdfIn PDF document text
    • http://fojefefipo.22web.org/nukesa.pdfIn PDF document text
    • http://badge-verification-center.com/american_football_league_team_records07rz1.pdfIn PDF document text
    • https://cdn.sqhk.co/sibamoxa/oSRgggi/lifeb.pdfIn PDF document text
    • http://verenica.net/66825595083s2c3f.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://dizogabage.rf.gd/alight_motion_for_pc.pdfIn PDF document text
    • http://rimefuvax.epizy.com/62492628375.pdfIn PDF document text
    • http://xesijapapun.rf.gd/nier_automata_ending_e_guide.pdfIn PDF document text
    • http://jiboleramar.epizy.com/hp_probook_6470b_user_guide.pdfIn PDF document text
    • http://sokevigaku.rf.gd/9550584344.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_off0000cdb0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCDB0 5956 bytes
SHA-256: fff2268106393d71fef2383be402bb459e84e722da128261ea9f3630f1a548e6
font_01_sfnt_off0000e1e9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE1E9 14260 bytes
SHA-256: d436f1a4f11b5b10a8a78d455c8e9fcb7853070ad789f647a386ac5707c46870

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