Malicious PDF — malware analysis report

Static analysis result for SHA-256 b9f411c7d855b315…

MALICIOUS

PDF

95.7 KB Created: 2021-09-16 12:56:26 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-26
MD5: eecc54d15a3966225e4530673cd650b0 SHA-1: 743951c137a310bf491e6cb37067efa833015fee SHA-256: b9f411c7d855b315a41c70687fb6d2a1f309942952c73ed75f872375b137df0e
96 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

This PDF file was identified as malicious by an ML classifier and contains numerous external links. Several heuristics indicate that these links point to compromised WordPress upload directories and disposable hosting, suggesting a link farm or SEO spamming operation. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, providing no clear user-facing content but containing embedded URI information.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9965

Heuristics 5

  • 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.
  • 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://infrive.ru/uplcv?utm_term=android+emulator+no+graphics+card PDF link annotation
    • https://www.sgestrecho.es/wp-content/plugins/formcraft/file-upload/server/content/files/1613c746135929---vutuwajilerajosepa.pdfIn PDF document text
    • http://stapper.de/sites/default/files/userfilesfile/xonagunisirixi.pdfIn PDF document text
    • http://rydelko.pl/userfiles/file/139582513.pdfIn PDF document text
    • https://k-barrierfree.com/FileData/ckfinder/files/20210912_8066B2F837ACFF47.pdfIn PDF document text
    • https://nationalcardsolutions.com/wp-content/plugins/formcraft/file-upload/server/content/files/16131be900f6aa---75752478395.pdfIn PDF document text
    • https://vmkstroi.ru/wp-content/plugins/super-forms/uploads/php/files/0a37a3ef9c96256db6901abd4ccde1df/21938930809.pdfIn PDF document text
    • http://www.realisthotel.com/wp-content/plugins/formcraft/file-upload/server/content/files/1612efe061024a---rabetituzile.pdfIn PDF document text
    • https://specialgarden.ro/userfiles/file/49831248959.pdfIn PDF document text
    • http://zjqzzx.com/uploadfile/file/2021090511552373499.pdfIn PDF document text
    • http://for-rent-antwerp.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613b16e4e1f28---pinenagigexawobonofame.pdfIn PDF document text
    • https://mtestbd.com/assets/uploads/files/3305364268.pdfIn PDF document text
    • http://cuacuontoanthang.com/media/file/tepuzobepejuwagu.pdfIn PDF document text
    • http://oskarmak.com/userfiles/file/59683203330.pdfIn PDF document text
    • http://humanitool.ru/userfiles/file/debesobefekoxesav.pdfIn PDF document text
    • https://kirbas.com/img/uploaded/file/64769764873.pdfIn PDF document text
    • http://boki.hu/editor_up/nitetejewe.pdfIn PDF document text
    • http://stsaischoolamritsar.com/slbdavbatala/userfiles/file/zuvonifozelakegamod.pdfIn PDF document text
    • https://yellowstonewildlife.com/69907470858.pdfIn PDF document text
    • http://omgmediatank.com/userfiles/files/gunowal.pdfIn PDF document text
    • https://hondamienbac.vn/userfiles/file/wifazu.pdfIn PDF document text
    • https://sysyanginguvenlik.com/uploads/files/29520415686.pdfIn PDF document text
    • https://noks.cz/wp-content/plugins/formcraft/file-upload/server/content/files/16140a34724572---vakesexivogivux.pdfIn PDF document text
    • http://jjkxmy.com/upload/files/202109100851216673.pdfIn PDF document text
    • https://fotobolfestmeny.hu/mvc/userfiles/file/xomozupozox.pdfIn PDF document text
    • https://accesoriosalmayor.com/images/userfiles/file/23193250583.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://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_off000111d3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x111D3 11040 bytes
SHA-256: 5ef665cc9d795b055efbabc3eaafe0b958a9e4c272de84e89138744e995bda87
font_01_sfnt_off00012b26.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12B26 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00014338.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x14338 17604 bytes
SHA-256: 78b52aed2765f28815b7eb27eaf02ae0130e4d487420901cf6d003ab272fef9b

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