Malicious PDF — malware analysis report

Static analysis result for SHA-256 31b1d42f0f218b04…

MALICIOUS

PDF

67.5 KB Created: 2021-06-20 00:06:46 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-24
MD5: f6a89d8b768b0d68dffcd974f634bef2 SHA-1: 26dff899155b1eb6c31b8202265c405150d787e7 SHA-256: 31b1d42f0f218b0495dca0667dea50dc0a5d95545f07559088af513abe173135
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

This PDF file was flagged by multiple heuristics as malicious, including a high-confidence ML classifier and ClamAV detection. It contains numerous embedded URLs that point to compromised CMS upload storage, suggesting it functions as a link farm. The document body is heavily obfuscated and contains metadata indicating it was generated by wkhtmltopdf, a tool often used to create malicious PDFs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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 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://auf.vn/wp-content/plugins/super-forms/uploads/php/files/ud8eskckc1hq447vurlvnmcol4/90124910133.pdf In PDF document text
    • https://ecef-groupe.com/wp-content/plugins/super-forms/uploads/php/files/assqrhadvd4a6vqhkqm97n6bt1/52025342205.pdfIn PDF document text
    • http://www.ncstarim.com.tr/wp-content/plugins/super-forms/uploads/php/files/bb1orgcee8pkthht04hichmtf5/13320111194.pdfIn PDF document text
    • https://aquariumfargo.com/wp-content/plugins/super-forms/uploads/php/files/149d495b151b9e076dc41ea9ab14bf99/tuxebi.pdfIn PDF document text
    • http://csc0512.com/userfiles/file/20210612144807_bp2rv2.pdfIn PDF document text
    • https://amursvoidom.ru/media/files/wagajuvi.pdfIn PDF document text
    • http://starlightcelebre.org/clients/4/43/43e9139217482d7666ce300faf566241/File/95127616694.pdfIn PDF document text
    • http://w-f-l.de/user_img/file/wonokasebekafoxexad.pdfIn PDF document text
    • http://crystalnymph.by/wp-content/plugins/super-forms/uploads/php/files/8e9a016f16a1f9832f1d318938211b56/kofofubenobuwone.pdfIn PDF document text
    • http://europeanprofservices.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608459a2bee3b---dedesogabevurasib.pdfIn PDF document text
    • https://cal.lighting/wp-content/plugins/super-forms/uploads/php/files/d47c3fe9c06d6f6b929b5e6857f628cc/43104547336.pdfIn PDF document text
    • http://chongthamnguoc.vn/img/files/pelitibagimum.pdfIn PDF document text
    • https://acronimocostanzo.com/userfiles/file/firolugosopenepusovi.pdfIn PDF document text
    • https://nhaban24h.com.vn/wp-content/plugins/super-forms/uploads/php/files/ldg5bb9r9815bap66jl4dshcji/23780887532.pdfIn PDF document text
    • https://member-amz-seller-system.de/wp-content/plugins/super-forms/uploads/php/files/ff02474a2c8c534bdc61112d9a4a692c/37696039783.pdfIn PDF document text
    • https://www.nestroots.com/wp-content/plugins/super-forms/uploads/php/files/155i6aoae52cd4q0au46np6564/xubovatesenobutos.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/Om9ozkHLxGw/uplcv?utm_term=siberian+mouse+fullPDF 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000ca7e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCA7E 5156 bytes
SHA-256: fb1875231e3ac8fd84a93091d5c68a025d357cd016599df5f772744a1ab55a0f
font_01_sfnt_off0000dbeb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDBEB 11620 bytes
SHA-256: dc52de4fa26ba90003a8741545e60b009166c946e8cb23b71007a99a467fbce8