Malicious PDF — malware analysis report

Static analysis result for SHA-256 6141c81784ff494b…

MALICIOUS

PDF

70.8 KB Created: 2021-09-29 02:18:13 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-26
MD5: c8d753c637fca151efdcbde6f7fb964f SHA-1: 562119d0a400aa3eac34b3cae6b27e0686f7486e SHA-256: 6141c81784ff494bf6373d51c65446a34b89bcda81b9bc547ddb10bdbe72f3d5
126 Risk Score

Malware Insights

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

The sample is identified as a malicious PDF by ClamAV and an ML classifier. It contains numerous embedded URLs, many of which point to PDF files hosted on various domains, suggesting a link farm or redirection mechanism. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' strongly indicates this malicious intent. No scripts were extracted, and the document body was unreadable, but the overall structure and URL patterns point to a phishing or malware distribution lure.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9975

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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.
  • 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://erh-hu.com/userfiles/file/banujiwafodozage.pdf In PDF document text
    • http://starinviter.com/ckimagefiles/29169673562.pdfIn PDF document text
    • http://aihyang.com/userfiles/file/rubogigavasosupilakesewiw.pdfIn PDF document text
    • http://www.romanschatztruhe.de/img/files/voweporagug.pdfIn PDF document text
    • http://sistersaviopublicschool.com/userfiles/file/xusadafetaruzelowirasofu.pdfIn PDF document text
    • https://brylka-kfz.de/wp-content/plugins/formcraft/file-upload/server/content/files/1614b37ac61b69---65045713052.pdfIn PDF document text
    • http://ride.hu/images/uploads/files/50339673528.pdfIn PDF document text
    • https://gedayapi.com/userfiles/file/namiked.pdfIn PDF document text
    • https://kompaspt1.com/contents/files/97394662993.pdfIn PDF document text
    • http://nsmpublicschool.org/slbdavbatala/userfiles/file/15464984274.pdfIn PDF document text
    • http://mopi.eu/ckfinder/userfiles/files/veneriluwukezaputet.pdfIn PDF document text
    • http://ledlight-lamp.com/mingyi/images/userfiles/file/26066121271.pdfIn PDF document text
    • http://www.bargiel.com.pl/ckfinder/userfiles/files/raxipusekitanuvip.pdfIn PDF document text
    • http://studiofapas.it/userfiles/files/84753228409.pdfIn PDF document text
    • http://vinaaquachem.com/uploads/files/rokuvopitusanewefa.pdfIn PDF document text
    • https://successstudio.net/userfiles/file/funofeza.pdfIn PDF document text
    • http://korsorlampang.net/user_img/files/29219422906.pdfIn PDF document text
    • http://gianphoiduyloimodel.com/Images_upload/files/larumolibisexa.pdfIn PDF document text
    • http://szyoujin.com/UploadFile/file/20210902191952217.pdfIn PDF document text
    • http://andrenickels.de/ckfinder/userfiles/files/22775058440.pdfIn PDF document text
    • http://adhdesign.de/userContent/files/20210928235454-kadafeduwarixebosa.pdfIn PDF document text
    • http://china-zub.ru/userfiles/file/zijonovenaz.pdfIn PDF document text
    • https://sailstudy.in/ckfinder/userfiles/files/5166478085.pdfIn PDF document text
    • https://soenen-pneus.com/upload/file/larovipuvudur.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/PmAiG5ZyT-k/uplcv?utm_term=android+data+recovery+apk+for+pcPDF 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_off0000b1c1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB1C1 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000c9d8.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC9D8 10652 bytes
SHA-256: 21eed0e3475bf5eca7137d348538acf4f30061a1daf316dd7316145cb9517871
font_02_sfnt_off0000e261.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE261 16032 bytes
SHA-256: 74bef917094eef2fd7b25d6e299bf9eab9b44f69b18d442b09f6c1648358ce9d