Malicious PDF — malware analysis report

Static analysis result for SHA-256 7821bdf15e083b8b…

MALICIOUS

PDF

73.1 KB Created: 2021-09-16 01:46:39 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: 896808ac1511204c5fdbcd663c6369d0 SHA-1: b6945bb83721bf4c448999680ed6fdf8d19e0436 SHA-256: 7821bdf15e083b8bd29742f10413d0d1c3ddb3941a2c4f37384f950755894d71
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF was flagged by ML classifiers and ClamAV as malicious, containing numerous embedded URLs pointing to a link farm hosted on disposable domains. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' indicates a deliberate attempt to manipulate search engine results or distribute malicious content through a network of linked PDFs. While no scripts were explicitly extracted, the nature of the embedded URLs and the link farm heuristic strongly suggest a phishing or malware distribution vector, likely initiated via spearphishing attachment.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9985

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 https://allytemp.ru/uplcv?utm_term=find+the+derivative+of+e PDF link annotation
    • http://www.191seo.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613fb519291c5---94137732331.pdfIn PDF document text
    • http://permanentnimakeup-brno.cz/userfiles/files/tumotagifixawezipokuso.pdfIn PDF document text
    • http://www.aamuhsv-madisonalumni.org/files/files/jaxavaxedosak.pdfIn PDF document text
    • https://vietnaminsight.biz/ckfinder/userfiles/files/16991488867.pdfIn PDF document text
    • https://beldapromosyon.com/calisma2/files/uploads/8184416482.pdfIn PDF document text
    • http://powercleanperu.com/cms_powerclean_2015/sgi_userfiles/userfiles/files/tomexadisumew.pdfIn PDF document text
    • http://bjhtdszdh.com/v15/Upload/file/20219141649195851.pdfIn PDF document text
    • https://digireg.dk/upload/33702465279.pdfIn PDF document text
    • https://altinhediyeler.com/calisma2/files/uploads/77743089220.pdfIn PDF document text
    • https://zagorjeadventureteam.hr/files/falupapo.pdfIn PDF document text
    • http://dedanskecasinoer.dk/userfiles/file/taxuvifabavesuzoreroz.pdfIn PDF document text
    • http://onlinecommerce.bg/uploads/pages/files/17438127817.pdfIn PDF document text
    • http://thayloilocnuoctaihanoi.net/upload/files/19263390356.pdfIn PDF document text
    • https://cortopolis.ar/userfiles/file/nopusolibuka.pdfIn PDF document text
    • https://fedico.ca/upload/editor/file/64876412164.pdfIn PDF document text
    • http://bielwod.com/userfiles/file/63685834808.pdfIn PDF document text
    • http://grapes4u.ca/sites/all/sites/grapes4u.ca/files/44360600800.pdfIn PDF document text
    • http://alphanaturehk.com/userfiles/file/75163406601.pdfIn PDF document text
    • https://zoorichi.com/temp/fckeditor/file/9408514863.pdfIn PDF document text
    • http://ks4073.com/file_media/file_image/file/2934987204.pdfIn PDF document text
    • http://kondicionery-vidnoe.ru/upload_picture/file/falimod.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_off0000bdf1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBDF1 10280 bytes
SHA-256: f20c81da925d132536a3ea5a237573d15365477f360676f514a742854cd35fd7
font_01_sfnt_off0000d4f9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD4F9 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000ed0b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xED0B 16400 bytes
SHA-256: 1f9e496ffba2a0670ff151125f262812f3d20382224ffd8b639274c353270c2f