Malicious PDF — malware analysis report

Static analysis result for SHA-256 a4a31b22f3164012…

MALICIOUS

PDF

71.7 KB Created: 2021-04-01 23:27:09 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: ac732ffaff28deba4e9a97038cf839b7 SHA-1: dc7664bf4fe2377f3ef98900577b0efebfc054f5 SHA-256: a4a31b22f31640120345ba5f9c47054539f3c1e13d77065a25ec3e28b2537186
156 Risk Score

Malware Insights

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

The PDF file contains numerous external links, with a critical heuristic identifying it as a "PDF_SEO_LINK_FARM" designed to host a large number of PDF files. One of the primary URLs, 'https://golowaki.ru/wix?keyword=function+composition+worksheet+answer+key', is presented as a worksheet answer key, a common lure. ClamAV detection and ML classification strongly indicate malicious intent, likely phishing or malware distribution.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://golowaki.ru/wix?keyword=function+composition+worksheet+answer+key
    • https://cdn.sqhk.co/jikikavadaja/aYihhhS/donate_bed_sheets_to_goodwill.pdf
    • https://cdn-cms.f-static.net/uploads/4458125/normal_6009e3101c7cf.pdf
    • https://cdn-cms.f-static.net/uploads/4366385/normal_60462b9804652.pdf
    • https://cdn.sqhk.co/wevafofed/ifYjgje/encyclopedia_brown_boy_detective_lexile_level.pdf
    • https://static.s123-cdn-static.com/uploads/4470964/normal_5fec878bd0c9a.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/564870c2-fe82-435b-b77b-05f7d23a7d71/how_to_be_a_good_child_care_director.pdf
    • https://uploads.strikinglycdn.com/files/adf0e389-aaf9-4223-8130-b5b949a6e2b8/peer_gynt_morning_free_sheet_music_piano.pdf
    • https://s3.amazonaws.com/livivuvuwugeb/toterazetazafemilimowado.pdf
    • https://uploads.strikinglycdn.com/files/3847b0b6-0877-4cbb-894a-0df57fa5bf94/essential_oils_pocket_reference_guide.pdf
    • https://s3.amazonaws.com/sizabo/kiliv.pdf
    • https://2e8e3215-33bf-4fe1-bc67-b38dac560527.filesusr.com/ugd/269bb8_37ae112c3ccb4950b56eef112c5a1451.pdf?index=true
    • https://b3695a61-a5b7-457a-863f-99677d03e0cc.filesusr.com/ugd/f2a82d_5722c2d6b7b7479682bef086b58278b7.pdf?index=true
    • https://s3.amazonaws.com/tapexiw/lexuveke.pdf
    • https://uploads.strikinglycdn.com/files/fe94e967-8a74-464d-88ca-341fdd1f0def/35732839600.pdf
    • https://uploads.strikinglycdn.com/files/8812deec-8bcd-443a-b841-470532fd5b13/duxavin.pdf
    • https://uploads.strikinglycdn.com/files/499a5388-9de0-4754-92fa-155ca2e36deb/royal_mail_international_tracking_contact_number.pdf
    • https://uploads.strikinglycdn.com/files/3f2275fd-d13d-4be2-9c1a-72da69176558/how_to_change_a_wick_in_a_square_kerosene_heater.pdf
    • https://uploads.strikinglycdn.com/files/56321407-0368-4f90-84e4-7e14997d5225/ipad_mini_2020.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_off0000dbd7.bin
88b3e8b1da19fcdb70e8e9e50e4b2e79d261b03744f72ea211945ab75530b71d		 pdf-font-stream PDF embedded font (sfnt) at offset 0xDBD7 5356 bytes
font_01_sfnt_off0000edfe.bin
d572d63d22602fc2dfb6474155bdf73a755397a25f7f594ba00325c681d89bc8		 pdf-font-stream PDF embedded font (sfnt) at offset 0xEDFE 10400 bytes

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