Malicious PDF — malware analysis report

Static analysis result for SHA-256 91a8a110f8230331…

MALICIOUS

PDF

85.2 KB Created: 2021-09-11 17:57:05 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-24
MD5: c13d66676ca79222c34622317eb6e76d SHA-1: 3be376d9e3d7e7f9d5d18b1f3b6e23773c6fe524 SHA-256: 91a8a110f8230331bb246b7a0053d49499794414281c1775fe20a346dd4d9633
134 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains embedded JavaScript and numerous external URIs, with a high ML classifier score and ClamAV detection indicating malicious intent. The heuristics suggest it functions as a link farm, directing users to various external PDF files, one of which is hosted on 'konstruktor33.ru'. The embedded JavaScript likely facilitates the redirection or further malicious actions.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9961

Heuristics 6

  • 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.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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://konstruktor33.ru/app/webroot/files/files/jolevo.pdf In PDF document text
    • http://hdurmuslar.com/images_upload/files/9573419886.pdfIn PDF document text
    • http://powerfalcon.net/uppic/files/84599155551.pdfIn PDF document text
    • https://esperanzadeavila.com/fotos/file/50693983593.pdfIn PDF document text
    • http://madmojo.com/fckupload/file/jubeximijuxod.pdfIn PDF document text
    • http://joltiy.ru/uploads/files/83624441251.pdfIn PDF document text
    • http://armiikrajowej36.pl/public/upload/ckfinder/userfiles/files/bifinoj.pdfIn PDF document text
    • http://piannocreativo.com/js/new/fckeditor/userfiles/file/58626371720.pdfIn PDF document text
    • http://liga-stf.ru/i/upload/files/moxejigunejadoxo.pdfIn PDF document text
    • http://visusmarble.com/images_upload/files/61356625370.pdfIn PDF document text
    • http://club-integra.ru/userfiles/file/4930801153.pdfIn PDF document text
    • http://www.southforconstruction.com/frontend/web/ckfinder/userfiles/files/lidab.pdfIn PDF document text
    • https://testpensija.bankai.lv/ckfinder/userfiles/files/38659081154.pdfIn PDF document text
    • http://take114.kr/FileData/ckfinder/files/20210908_48C8E4183204EBD7.pdfIn PDF document text
    • http://jsushibrea.com/uploads/files/56677941659.pdfIn PDF document text
    • https://jdsliquorlocker.com/nbloom/fckuploads/file/zavimilezizaguwiletovof.pdfIn PDF document text
    • https://superpart.com/files/vejotepakumawuruf.pdfIn PDF document text
    • https://cytokin.ca/upload/editor/file/26586403060.pdfIn PDF document text
    • https://marblo.ph/app/webroot/img/files/85266270590.pdfIn PDF document text
    • https://telechips.com/ckfinder/userfiles/files/jorometolimof.pdfIn PDF document text
    • https://www.mercato.co.za/wp-content/plugins/formcraft/file-upload/server/content/files/1613b2f7ec6b8a---47623573822.pdfIn PDF document text
    • http://www.ernakulamarchdiocese.org/www/js/ckfinder/userfiles/files/4360849832.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/FevRqgeaUVY/uplcv?utm_term=tycoon+business+game+modPDF 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_off0000e81e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE81E 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off00010030.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10030 18092 bytes
SHA-256: 4a33502153220098eed045cc410f442fc095ad9aa1614bc0752be6400308cba8
font_02_sfnt_off00012ee3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12EE3 10788 bytes
SHA-256: 5d9a6fe75457bef007d4e3e750e6b8ec11e76bc8b4de186a7086307c0e971684