Malicious PDF — malware analysis report

Static analysis result for SHA-256 a8504e72602a9b6d…

MALICIOUS

PDF

79.2 KB Created: 2021-09-05 07:04:56 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 929a12f7a88b7a37224129b61a57684b SHA-1: c55680e9c1bdefcf3687271a96dd2e4d45a5d4dd SHA-256: a8504e72602a9b6d95438cd068662d0c498b1283f77139ed897736eb37f56236
164 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF contains numerous embedded URLs, many of which point to compromised WordPress sites and disposable hosting, indicating a link farm designed to distribute malicious content. The ML classifier and ClamAV detection strongly suggest malicious intent, likely phishing or malware distribution via these links. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, providing no direct user-facing content but serving as a vessel for the malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9981

Heuristics 7

  • 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.
  • Urgency / deadline lure low SE_URGENCY_LURE
    Document contains urgency or deadline language ('account will be terminated', 'action required within 24 hours', etc.) — useful context, but low-signal without other findings
  • 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.hospedeagora.com.br/wp-content/plugins/super-forms/uploads/php/files/eqkg7v7a5sheb697v1jv033eu7/79532039677.pdf In PDF document text
    • http://www.infranetltd.com/wp-content/plugins/formcraft/file-upload/server/content/files/160f13c6d4b35d---vabevapilekawapiwame.pdfIn PDF document text
    • https://vakukh.ru/wp-content/plugins/super-forms/uploads/php/files/483453dd839d5bd64912e00a0c5f903c/74631863799.pdfIn PDF document text
    • http://abovomedia.hu/_user/file/figudemijax.pdfIn PDF document text
    • http://inwama4.vn/webroot/img/files/94721196017.pdfIn PDF document text
    • https://xn----8sbaavnccwq4am.xn--p1ai/wp-content/plugins/super-forms/uploads/php/files/c90abe6f1268a6a0c50b908c22671267/18966605216.pdfIn PDF document text
    • http://www.jhannahs.com/wp-content/plugins/formcraft/file-upload/server/content/files/161067ffa8a46b---dijubabogonizamixusiw.pdfIn PDF document text
    • https://creativesilhouettes.ca/wp-content/plugins/formcraft/file-upload/server/content/files/160f35ee7e8c7b---88053808690.pdfIn PDF document text
    • http://droneducational.com/admin/userfiles/file/66786898792.pdfIn PDF document text
    • https://cutletsmeat.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607f22b10b307---53950947511.pdfIn PDF document text
    • https://allianceflooring.net/wp-content/plugins/super-forms/uploads/php/files/8bc0203c03db861374e539fb2140ee4f/85064546407.pdfIn PDF document text
    • https://agencement-menuiserie-var.fr/stockages/files/70941497470.pdfIn PDF document text
    • https://skvely-kup.cz/files/file/26145816016.pdfIn PDF document text
    • https://landlorddebtadvisory.com/wp-content/plugins/super-forms/uploads/php/files/36qi05685nnph2lum7q4d32mf3/goxusolurako.pdfIn PDF document text
    • https://deedpoll.sg/wp-content/plugins/super-forms/uploads/php/files/0a4af8e6beb22838073b3be27e319fcd/tabisuwidazowibofidujirex.pdfIn PDF document text
    • http://ap116.ru/userfiles/file/guvisiwu.pdfIn PDF document text
    • https://hinodanang.com/uploads/image/files/jubufibajidasukirurozas.pdfIn PDF document text
    • https://ispartaprefabrik.com/ckfinder/upload/files/jezete.pdfIn PDF document text
    • https://www.ideaklinik.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607b630541546---39781193075.pdfIn PDF document text
    • http://incomsistema.ru/ckfinder/userfiles/files/sifizazexeluzimemuvojem.pdfIn PDF document text
    • http://naturallabs.de/userfiles/file/jaregerasi.pdfIn PDF document text
    • http://soflacops.com/clients/83266/File/9244758547.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/GLLx1DTH0VQ/uplcv?utm_term=immunization+schedule+in+tanzania+pdfPDF 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_off0000d3f9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD3F9 10896 bytes
SHA-256: 786e21d3c37f97c99b2209ca594b56fc1edf3b50f44fcb9b74b0d4c59f7df437
font_01_sfnt_off0000ed02.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xED02 16260 bytes
SHA-256: 7b519c393f3391275712776193c73e3057e5dc7f64ac2d0e708f07428d1d2c41
font_02_sfnt_off00011700.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11700 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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