Malicious PDF — malware analysis report

Static analysis result for SHA-256 bb19c1c64c200f37…

MALICIOUS

PDF

81.4 KB Created: 2021-09-20 11:57:53 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-27
MD5: 43d7d9d297b0517c177c058f3dd5a25f SHA-1: 490e0ae66ab940c3d1594a482b49886dc008bb2f SHA-256: bb19c1c64c200f37adffaeee191410da078d2139d3788302e7e584287f5e149c
166 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF file identified as malicious by ML classifiers and ClamAV. It contains numerous links to external PDFs hosted on various domains, many of which appear to be disposable or low-reputation. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' strongly suggests this is a link farm designed to obscure the true malicious destination. While no scripts were explicitly extracted, the nature of the links and the ML detection point towards a phishing or malware distribution attempt.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9985

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • PDF link to algorithmically-generated URL high PDF_RANDOM_URL_LINK
    PDF contains a clickable HTTP(S) link whose host looks algorithmically generated (pronounceable-random labels) and whose path/query carries a long high-entropy token. This is the randomized-redirector pattern of malspam phishing lures — the visible document is only a prompt — not a PDF parser vulnerability.
  • 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://ambulatorioveterinariosantanna.eu/userfiles/files/bitita.pdf In PDF document text
    • https://taucaotoccatba.vn/images/news/files/99469747879.pdfIn PDF document text
    • http://ansonseatery.com/uploads/files/64901175942.pdfIn PDF document text
    • http://santamariamikado.com/uploads/files/wofebaxomiramipakemadema.pdfIn PDF document text
    • http://polipack.ru/content/file/wafaxajetumabepam.pdfIn PDF document text
    • http://www.fliesen-brill.de/wp-content/plugins/formcraft/file-upload/server/content/files/161443e69ae8b9---46559066851.pdfIn PDF document text
    • http://bjdfszwy.com/filespath/files/20210916210426.pdfIn PDF document text
    • https://indiantiffin4me.com/nbloom/fckuploads/file/tibakamubobu.pdfIn PDF document text
    • http://brlairport.com/images/file/24747073238.pdfIn PDF document text
    • http://studioriggio.it/userfiles/files/16922560896.pdfIn PDF document text
    • http://malbreil.com/userfiles/file/15463817378.pdfIn PDF document text
    • http://esteticka-stomatologie.cz/files/content/file/78099432789.pdfIn PDF document text
    • http://aa-nusd.jp/58175316041.pdfIn PDF document text
    • https://zlato-eu.cz/upload/files/talezokefad.pdfIn PDF document text
    • http://tikatalog.sk/_files/file/80397736875.pdfIn PDF document text
    • http://opusincertum.it/userfiles/files/rinarufofofujatufurutu.pdfIn PDF document text
    • https://candica.pl/ckfinder/userfiles/files/jubijufamebobozokonas.pdfIn PDF document text
    • https://rrr71.ru/upload_picture/11126491842.pdfIn PDF document text
    • http://vonschickenfremont.com/uploads/files/tedemame.pdfIn PDF document text
    • http://vibrobreaker.com/files/files/5794927168.pdfIn PDF document text
    • http://www.anieliasfx.com/uploads/textareas/file/wogefemokivanit.pdfIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/1KS0DP0cxss/uplcv?utm_term=big+cash+apk+appPDF 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_off0000db90.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDB90 17392 bytes
SHA-256: ce1be2d8c9afa6d42398d6ab9d72b3323a6a2c61e57098151709309e7119bc54
font_01_sfnt_off00010906.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10906 10196 bytes
SHA-256: 43c321a2ac11ce09bd48439e4475a68cded3b74eca547c259e6517e25a258647
font_02_sfnt_off0001200f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1200F 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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