Malicious PDF — malware analysis report

Static analysis result for SHA-256 b4ab6cd73b2658c9…

MALICIOUS

PDF

84.2 KB Created: 2021-09-05 13:54:38 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: a4fde6b45cbcc876fcc1ce07b2c7b68e SHA-1: 13a7542d1b6de2dbb508b3cdde52341585bed123 SHA-256: b4ab6cd73b2658c9a58124f5609f7eace4b2c43cf4d8c43cc7a3e121a70cb7d4
104 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF file contains numerous links pointing to compromised WordPress upload directories and other disposable hosting sites, suggesting a link farm designed to distribute malicious files. The ML classifier strongly flagged this PDF as malicious, and the presence of multiple PDF_SEO_DISPOSABLE_LINK_FARM and PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM heuristics further supports this assessment. The document body is heavily obfuscated and does not provide clear textual lures, but the overall structure and heuristic firings indicate an attempt to trick users into downloading further payloads.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9860

Heuristics 6

  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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.
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • 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 http://brilliantsolarpaneling.com/userfiles/file/roruwixedes.pdf In PDF document text
    • http://penzionklara.cz/userfiles/file/sevaxuxiduretex.pdfIn PDF document text
    • http://bhsclassof70.com/clients/a/ac/acf0241a72c9eb28a719a759cf8a4748/File/30949054532.pdfIn PDF document text
    • https://amerismithenterprises.com/wp-content/plugins/super-forms/uploads/php/files/8be2a27cfc8d03a18c9d5d21e5a8e921/94966393491.pdfIn PDF document text
    • https://taxiparga.com/wp-content/plugins/super-forms/uploads/php/files/943735efc7e91147335b286888cc9094/78044641564.pdfIn PDF document text
    • http://ondrejkocar.cz/img/file/juvetajutivi.pdfIn PDF document text
    • http://www.mearesandassociatesllc.com/siteuploads/editorimg/file/67049702295.pdfIn PDF document text
    • http://friluftsgruppen.se/wp-content/plugins/formcraft/file-upload/server/content/files/160707034d4728---10557809285.pdfIn PDF document text
    • https://www.traveltimevipp.com/wp-content/plugins/super-forms/uploads/php/files/d89f96f9bb672025b459c651e994b457/kimiximikekokiw.pdfIn PDF document text
    • http://cp-1.ru/userfiles/files/sevifepukib.pdfIn PDF document text
    • http://j1medical.com/uploaded/file/bulijuga.pdfIn PDF document text
    • https://agribusiness.pk/wp-content/plugins/formcraft/file-upload/server/content/files/1606fca39e4b14---9611308345.pdfIn PDF document text
    • http://www.consorcio.edu.pe/wp-content/plugins/formcraft/file-upload/server/content/files/160e0efd5a946f---tugifo.pdfIn PDF document text
    • http://nsfeed.com/_UploadFile/Images/file/81727491239.pdfIn PDF document text
    • http://www.neslihanonur.com/wp-content/plugins/super-forms/uploads/php/files/e574481e6453c56158e6042977dbcb5b/jupuf.pdfIn PDF document text
    • http://bdn10.cz/files/file/bojekovisezoda.pdfIn PDF document text
    • http://doo-san.com/userfiles/file/20210526032727.pdfIn PDF document text
    • http://studiovalentini.eu/userfiles/files/bikab.pdfIn PDF document text
    • http://gpszone.hu/upload/userfiles/file/kawababoturuteb.pdfIn PDF document text
    • http://www.hkqi.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607d6d0e295cc---zozafuravazefawoxox.pdfIn PDF document text
    • https://singlespeed-switzerland.ch/userfiles/files/47180386088.pdfIn PDF document text
    • http://amfmeg.org/wp-content/plugins/formcraft/file-upload/server/content/files/160f2f0741767a---58422058813.pdfIn PDF document text
    • https://www.bountyvacation.com/wp-content/plugins/formcraft/file-upload/server/content/files/16080781931c69---8927660214.pdfIn PDF document text
    • http://snookerfootball.eu/wp-content/plugins/formcraft/file-upload/server/content/files/1606f0aa13293d---82354107924.pdfIn PDF document text
    • https://upbilbao.com/ckfinder/userfiles/files/67076201209.pdfIn PDF document text
    • http://gorisum.net/fckeditor/upload_file/file/85023578985.pdfIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/ngfLrbzwjls/uplcv?utm_term=electronics+objective+book+pdf+downloadPDF link annotation
    • 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://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000de34.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDE34 19388 bytes
SHA-256: 79f796f854416d97238cd146bd79d6c8c11a638903a4a7970b501387d8bb1e2b
font_01_sfnt_off000110d0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x110D0 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off000128e7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x128E7 11108 bytes
SHA-256: 3398bd5b069db987762b69bb72cbcd6e3a2b98370533148fdd5ddea643e46eef

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