Malicious PDF — malware analysis report

Static analysis result for SHA-256 3f9d11e8cf8c3afc…

MALICIOUS

PDF

76.6 KB Created: 2021-03-22 14:43:08 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 5e50158c2b6b1c1214f92b4be5159958 SHA-1: 4256264907d6dcf918b0a72f0df87cd52a9bace6 SHA-256: 3f9d11e8cf8c3afcc7530ae4de1cd7b6ea9519b6a61036163c4393629012e9b1
126 Risk Score

Malware Insights

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

The sample is a PDF file flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. It contains numerous embedded URLs, many of which point to disposable hosting and are presented as part of a "link farm". The document body, though heavily obfuscated, suggests a lure related to educational materials, likely to trick users into clicking these malicious links. No scripts were extracted, but the PDF structure itself facilitates the attack.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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 https://druttle.ru/award?keyword=sample+probability+questions+and+answers+pdf
    • http://terem.space/77415065865054a4.pdf
    • http://arfesopt.com/quiz_logo_game_answers_level_france_4jpbgb.pdf
    • http://naturalm.space/20315291209d4u73.pdf
    • http://wuxetij.mypressonline.com/writing_contests_for_high_school_students_2020_canada.pdf
    • http://udilische.club/morutivuwarokoxaro2ocy9.pdf
    • http://pihodze.com/ziraxim6n17e.pdf
    • http://webmastervlad.ru/votonoruginumiroworivisozar2vm.pdf
    • http://jirusulixozome.scienceontheweb.net/xesetirudegimikuwo.pdf
    • http://instapodarok365.site/1231688046795fy0.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://c5c27394-2042-4749-9b39-d1c24dcbd9f0.filesusr.com/ugd/e9b987_9f2046d8bd3b42b4bceb6093b7bbe60a.pdf?index=true
    • https://d5fd0048-bb8d-45a1-ba21-28d1cb0b7162.filesusr.com/ugd/5e8de6_c7be1148d4b14a3e8a8039e879591b92.pdf?index=true
    • http://zevusup.atwebpages.com/types_of_organizational_structure_in_management_science.pdf
    • https://s3.amazonaws.com/remufuzu/xamarin_forms_binding_property_programmatically.pdf
    • http://damedosa.rf.gd/account_format_excel.pdf
    • http://dupikupujetilu.rf.gd/zepazukorap.pdf
    • http://guriseb.myartsonline.com/lexilamugegapu.pdf
    • https://s3.amazonaws.com/vuzufexarevima/14463168651.pdf
    • http://fasujenijasezos.rf.gd/csv_to_google_sheets_python.pdf
    • http://zesafemumibow.myartsonline.com/how_to_use_pictochat_on_ds_lite.pdf
    • https://s3.amazonaws.com/gudukupir/can_adults_learn_piano.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000eb14.bin
6fb3a7f7e5f69cd4e2de60d1716d5ca5c72ee2ddd2c2e82e6635cb7d0efe1353		 pdf-font-stream PDF embedded font (sfnt) at offset 0xEB14 5752 bytes
font_01_sfnt_off0000fe9d.bin
7f076cdf54cd388cb3070a4756a80f17768607a9528347b08190165abf609702		 pdf-font-stream PDF embedded font (sfnt) at offset 0xFE9D 10584 bytes

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