Malicious PDF — malware analysis report

Static analysis result for SHA-256 a899b23ee5faa5b6…

MALICIOUS

PDF

72.8 KB Created: 2021-09-20 14:37:48 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-27
MD5: 03e5d8f1e8c12542f13fcb2e64775869 SHA-1: 106421353263156d60bd0b5e64b5c98ef55e47cb SHA-256: a899b23ee5faa5b6b56bbe380ed498d6d8acb3fcc65ec1a35921b45ee0e85a61
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file was detected as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous embedded URLs pointing to various domains, suggesting it functions as a link farm or redirection service. The PDF_SEO_DISPOSABLE_LINK_FARM heuristic further supports this, indicating a strategy to distribute links across disposable hosting. No scripts were extracted, but the presence of many external URIs suggests the primary attack pattern is to redirect users to potentially malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9985

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://chcial.ru/uplcv?utm_term=have+got+and+has+got+exercises+pdf PDF link annotation
    • http://teormech.ru/teormech/usrimg/file/rapolivefamijakapadowaji.pdfIn PDF document text
    • http://machinesupplier.cn/data/product/file/202198_31011_857.pdfIn PDF document text
    • http://xn--e1aaafipco3bk8gra3b.xn--p1ai/upload_picture/file/vizikuwebofozewuxira.pdfIn PDF document text
    • https://specializzati.tecnaevolution.it/dataload/ckupload/32875970320.pdfIn PDF document text
    • http://www.stallionreadymix.co.za/wp-content/plugins/formcraft/file-upload/server/content/files/161340a6adff92---57329272270.pdfIn PDF document text
    • http://viorina-deko.com/images/file/jukimebaden.pdfIn PDF document text
    • http://technestudio.eu/userfiles/files/dalujedatunaxopotigadofik.pdfIn PDF document text
    • http://ms-beauty.com/ckfinder/userfiles/files/69995486115.pdfIn PDF document text
    • http://htk2.altrodesign.eu/ckfinder/userfiles/files/34871730178.pdfIn PDF document text
    • http://travellerisland.com/files/64772962872.pdfIn PDF document text
    • http://vegasoft.hr/wp-content/plugins/formcraft/file-upload/server/content/files/161337c06e0a5c---xoguluzobajufovanuke.pdfIn PDF document text
    • https://cs168.tw/upfiles/editor/files/rapukolotujilaxifebexa.pdfIn PDF document text
    • https://cartolmania.it/file/57033770180.pdfIn PDF document text
    • http://momsystem.ru/public/file/kabolofejisosan.pdfIn PDF document text
    • https://karaari.leaddeehub.com/userfiles/files/39288253689.pdfIn PDF document text
    • http://archgeo-leszno.pl/uploads/userfiles/files/xokipusekazum.pdfIn PDF document text
    • http://thanhlapcongtykiengiang.com/upload/ck/files/jefefibupegonifipaxe.pdfIn PDF document text
    • http://studiotecnicobonoli.com/userfiles/files/kemurajefik.pdfIn PDF document text
    • http://mariautonoleggiomarsala.it/userfiles/files/92672004009.pdfIn PDF document text
    • http://www.thaiboat.net/image/upload/File/kuwimezitudorikonu.pdfIn PDF document text
    • http://china-engine.net/ckfinder/userfiles/files/32227651092.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_off0000bac0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBAC0 11012 bytes
SHA-256: 1014717ee84690b49e6abbaf09ef2d40ff72c9a0d09dae0378668855f74cf8c5
font_01_sfnt_off0000d416.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD416 16172 bytes
SHA-256: 2453a20a5f356afd1c5de05628d0dccc1b2ed2fd1e9e796547075b37e83cca0d
font_02_sfnt_off0000fdaa.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFDAA 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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