Malicious PDF — malware analysis report

Static analysis result for SHA-256 686bd0890b79c6d3…

MALICIOUS

PDF

79.6 KB Created: 2021-09-13 08:14:07 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: 2e9da1d7ca9821474f6ac8192a0e8740 SHA-1: 9d899e49977d312b0085ec9e7f95363d08b00403 SHA-256: 686bd0890b79c6d385288beb10cf8f62890bcb1e339ad5fdd2b48b3b76e588d5
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. The PDF contains numerous embedded URLs, many pointing to other PDF files hosted on various domains, suggesting a link farm or SEO poisoning tactic. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' specifically flags this behavior, indicating the PDF's purpose is to redirect users to a network of disposable hosting sites.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9992

Heuristics 5

  • 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.
  • 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://tckontrola.hr/files/97118570724.pdf In PDF document text
    • http://ecofincas.net/ckfinder/userfiles/files/69967574581.pdfIn PDF document text
    • https://limsurempat.com/contents/files/tisifaxaxobepamoto.pdfIn PDF document text
    • http://thekitchendesignstudio.org/uploads/files/dediz.pdfIn PDF document text
    • http://mkpstroitel.ru/upload/files/43785669101.pdfIn PDF document text
    • https://equator-maritime.com/userfiles/file/dogimuzemivovebukelusaji.pdfIn PDF document text
    • https://www.huaikrachaohospital.go.th/assets/global/lib/ckfinder/userfiles/files/91646486739.pdfIn PDF document text
    • http://fence-alarm.com/userfiles/files/makufixigurowa.pdfIn PDF document text
    • http://lawyermo.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/niwotirabinedefaga.pdfIn PDF document text
    • http://tw-tms.com/uploadpic/xw/files/74203429681.pdfIn PDF document text
    • http://qdsenfeng.com/data/files/32821407746.pdfIn PDF document text
    • https://efficientinfocomm.com/ckfinder/userfiles/files/sulolosasuz.pdfIn PDF document text
    • https://invision.buzyhub.com/files/wikuziwagibox.pdfIn PDF document text
    • http://marinda.ru/pics/images/file/jaxinuwojegema.pdfIn PDF document text
    • http://halaljones.com/uploads/files/49171528170.pdfIn PDF document text
    • http://poultech.net/d/files/62279292209.pdfIn PDF document text
    • http://eduomania.com/wp-content/plugins/formcraft/file-upload/server/content/files/16133a492d14d2---tonapufenaxe.pdfIn PDF document text
    • http://gardatrans.com/content/Files/95474354645.pdfIn PDF document text
    • http://kme-kme.cz/files/file/xopugewika.pdfIn PDF document text
    • https://hsdinstruments.nl/uploads/files/44779100676.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/1KS0DP0cxss/uplcv?utm_term=car+parking+all+cars+unlocked+apkPDF 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_off0000d171.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD171 10812 bytes
SHA-256: cb572f2db53429c0c145a13ffd46030f085ea852b05ed8369712b8e0f0caf9d7
font_01_sfnt_off0000ea41.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEA41 18004 bytes
SHA-256: 500fc1e3db1a28d98cee34494d6a5fe33c34a9880a2a26d5b86e778b3e593b8e
font_02_sfnt_off0001195b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1195B 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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