Malicious PDF — malware analysis report

Static analysis result for SHA-256 b821dabb0f4a3849…

MALICIOUS

PDF

69.9 KB Created: 2021-09-12 17:10:01 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 7f5a4443771e6b923564f1d478b71a60 SHA-1: d4037daeeaca684df1844a60cd27253824df35d6 SHA-256: b821dabb0f4a38499ee54de55c9ff883d4a64b6aaa0cb190861ce465825c9cd5
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF file identified as malicious by ClamAV and an ML classifier. It contains numerous embedded URLs, many of which point to compromised CMS uploads or disposable hosting, suggesting a link farm designed to redirect users to malicious content. The presence of PDF_SEO_DISPOSABLE_LINK_FARM and PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM heuristics further supports this. While no scripts were explicitly extracted, the nature of the embedded URLs and the PDF format itself often involves JavaScript for redirection or exploitation.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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://www.elementstraining.co.uk/wp-content/plugins/super-forms/uploads/php/files/j04u6u2c1fn62rq45aq7qlq77m/61179328694.pdf In PDF document text
    • http://maysoi.com/hinhanh_fckeditor/file/17966217012.pdfIn PDF document text
    • http://architettoannalisatinelli.it/userfiles/files/xerorogexukeduwe.pdfIn PDF document text
    • https://mtydizayn.com/userfiles/file/rogigi.pdfIn PDF document text
    • http://friluftsgruppen.se/wp-content/plugins/formcraft/file-upload/server/content/files/1613048a85bf4d---92037390193.pdfIn PDF document text
    • http://atut-biuro.com/uploaded/file/xilonevoritodeti.pdfIn PDF document text
    • http://splogservice.ru/content/files/bigokosisuxov.pdfIn PDF document text
    • https://vantainoidia.vn/ci/userfiles/files/61098765867.pdfIn PDF document text
    • https://ultralloy.net/upload/files/25455687999.pdfIn PDF document text
    • https://ecoverservice.be/gallery/file/supibojoja.pdfIn PDF document text
    • https://www.adler-leitishofen.de/wp-content/plugins/formcraft/file-upload/server/content/files/161386a229afbb---20124447156.pdfIn PDF document text
    • http://ridendo.cz/files/file/newokowoked.pdfIn PDF document text
    • http://diakmelo.hu/ckfinder/userfiles/files/kopobikaretolubat.pdfIn PDF document text
    • http://membranekeyboard.pl/_data/file/livazuziwezerewavigaz.pdfIn PDF document text
    • http://www.gcsystem.pl/wp-content/plugins/formcraft/file-upload/server/content/files/161351ac02c7b7---serovewejopabovovevider.pdfIn PDF document text
    • https://hotelpancharatna.com/assets/userfiles/files/81015767731.pdfIn PDF document text
    • https://cryptoshift.be/anaeter_capital/siteadmin/userfiles/files/4634934277.pdfIn PDF document text
    • https://mebelihome.ru/upload_picture/69478617455.pdfIn PDF document text
    • http://mega.kz/media/upload/files/57387726619.pdfIn PDF document text
    • http://mezon.jp/userfiles/file/wivexuv.pdfIn PDF document text
    • http://findmecakes.com/userfiles/files/61633639023.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/YTWXjIUwRh0/uplcv?utm_term=download+autocad+2019+for+mac+full+crackPDF 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_off0000aef0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xAEF0 10988 bytes
SHA-256: 11411065efc01f03ae5aa6f3a6aa8097279dec4a8055ad1d8ba837b56ea27784
font_01_sfnt_off0000c8a3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC8A3 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000e0b5.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE0B5 16280 bytes
SHA-256: 5804c4355c608d0e4a881c75a7188d5960822ec76d0d16464b35cd07df5d77aa