Malicious PDF — malware analysis report

Static analysis result for SHA-256 b494a7182c6e2ca4…

MALICIOUS

PDF

82.7 KB Created: 2021-02-19 17:23:01 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-16
MD5: 3764db883685f561e65b0795cba7d133 SHA-1: ad3523d7a10f3356ec9a0aa66ba6219c136a66f5 SHA-256: b494a7182c6e2ca41842f0d22f8ff3e71b64ce111d3788fb1ad4fb19f2e6f65f
126 Risk Score

Malware Insights

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

The PDF contains a large number of external links, many hosted on disposable domains, indicating a link farm designed to manipulate search engine rankings. The document body, though heavily obfuscated, contains a search query related to 'breakfast burritos' and metadata suggesting it was generated by wkhtmltopdf, which can be used to create documents that redirect users to external sites. The ML classifier strongly flagged this PDF as malicious, supporting the assessment of a malicious link farm.

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.
  • 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://maypoin.ru/123?utm_term=who+sells+breakfast+burritos PDF link annotation
    • http://giocodigital.website/titration_curves_of_amino_acids_lab_reportpd77h.pdfIn PDF document text
    • http://1xbet-regi.site/tamexavemebexazasirishy3l.pdfIn PDF document text
    • https://cdn.sqhk.co/simikimira/ggcnhjy/background_video_recorder_for_windows_10.pdfIn PDF document text
    • https://cdn.sqhk.co/tufuboloruj/jdhdjdW/ruwiraxikozosulo.pdfIn PDF document text
    • http://summer-italy.fun/human_body_parts_name_downloady9918.pdfIn PDF document text
    • https://witetalujoloxof.weebly.com/uploads/1/3/0/7/130740434/1738654.pdfIn PDF document text
    • http://ueuniti.xyz/fraction_division_word_problems_6th_grade9tvfl.pdfIn PDF document text
    • https://jovivikara.weebly.com/uploads/1/3/0/7/130740330/jamaligodogijekatamu.pdfIn PDF document text
    • https://bomoturu.weebly.com/uploads/1/3/1/3/131384468/cbd045ee0f4.pdfIn PDF document text
    • https://noserosajegupa.weebly.com/uploads/1/3/1/4/131453720/5662295.pdfIn PDF document text
    • https://nurinakeviwiket.weebly.com/uploads/1/3/1/4/131407921/mivedobade.pdfIn PDF document text
    • https://cdn.sqhk.co/nimuxugemu/IiefgdM/52779723538.pdfIn PDF document text
    • http://mx50off.pro/desene_animate_in_romana_bradul_de_c1x1ve.pdfIn PDF document text
    • http://luchdobro.site/equilibrium_of_forces_lab_report_discussion9zidk.pdfIn PDF document text
    • https://nenusobodi.weebly.com/uploads/1/3/1/4/131406558/f98eb049a.pdfIn PDF document text
    • http://smm-target.ru/akira_movie_free_300mbiw6kt.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://s3.amazonaws.com/tarajix/excel_spreadsheet_for_inventory_management_free.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_off00010650.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10650 5072 bytes
SHA-256: 40917f91e995a78bef96456464467af11c5023e04cb726d31476b316f6ccc7fd
font_01_sfnt_off00011795.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11795 11420 bytes
SHA-256: d0cdb1a0e8b05cd01abbd0cdd544f86ab7b22a3519ab85f7d61ff0f300c7dc0e

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