Malicious PDF — malware analysis report

Static analysis result for SHA-256 155341bf41e4eaec…

MALICIOUS

PDF

92.3 KB Created: 2021-08-31 20:29:13 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: 35ad9dad3e2a63b675b7b83aab3e01df SHA-1: e3861fac7c30890a6f0bd6f73d30549117d77efc SHA-256: 155341bf41e4eaec7ccfbd5d7a70e23ef3a2ea002ab8fcc4d9991eeffd1fcb58
176 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF was detected as malicious by ML classifiers and ClamAV, exhibiting characteristics of a callback phishing or tech-support scam. It contains a link farm pointing to numerous disposable URLs, many hosted on compromised WordPress sites, designed to redirect users. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, but the presence of PDF_URI and PDF_SEO_DISPOSABLE_LINK_FARM heuristics strongly suggests a lure mechanism.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9971

Heuristics 7

  • 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.
  • Callback phishing phone lure medium SE_CALLBACK_LURE
    Document asks the user to call a phone number in billing, refund, subscription, fraud, or security context — consistent with callback phishing or tech-support scam patterns. Suppressed for legitimate-issuer (IRS/gov/official-form) documents that carry no urgency or charge/dispute escalation.
  • 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://inwebjor.ru/uplcv?utm_term=ucsc+bookstore+hours PDF link annotation
    • http://thangmayedex.com/webroot/img/files/kofibap.pdfIn PDF document text
    • http://www.communityheroesproject.org/wp-content/plugins/formcraft/file-upload/server/content/files/16121ce8369ddd---tisixufud.pdfIn PDF document text
    • https://bluetact.com/locktactyuma/userfiles/file/faxipivawavezokiteme.pdfIn PDF document text
    • http://biosystech.com/pdsFck/file/29671318375.pdfIn PDF document text
    • https://www.espymetcalf.com/wp-content/plugins/formcraft/file-upload/server/content/files/160af8b6b74f52---zaruzifiz.pdfIn PDF document text
    • http://0575zl.com/userfiles/file/ripamazaguwidibez.pdfIn PDF document text
    • http://kledingindex.nl/images/uploads/butefuruwitovugalavejo.pdfIn PDF document text
    • https://levin-dent.ru/wp-content/plugins/super-forms/uploads/php/files/450269ccf06e0bf7d73b2fd2644e217e/najezipa.pdfIn PDF document text
    • https://kamber.dk/wp-content/plugins/super-forms/uploads/php/files/cdbeb574122c4625a253b69d62b71a28/pijazulukopurizotit.pdfIn PDF document text
    • http://amandamaitland.com/images/file/jixuzogitolemejefigine.pdfIn PDF document text
    • https://wavesmaroochydore.com/wp-content/plugins/super-forms/uploads/php/files/6ksoh10hi2hn5t6qlu2bpgpafr/97848430088.pdfIn PDF document text
    • https://namratalakhotia.com/userfiles/files/89730477482.pdfIn PDF document text
    • https://anthonygillant.com/userfiles/file/jajabaxez.pdfIn PDF document text
    • http://wm-meyer.de/meyer/admin/editor/ckfinder/userfiles/files/91483516773.pdfIn PDF document text
    • http://structurecreative.com/wp-content/plugins/formcraft/file-upload/server/content/files/160914a7992246---nodasaximinibu.pdfIn PDF document text
    • http://dges.in/userfiles/file/25725704203.pdfIn PDF document text
    • http://renknh.com/ckupload/files/fesifabal.pdfIn PDF document text
    • http://angelcabrera.com/FCKfiles/file/17494278559.pdfIn PDF document text
    • http://podlahypilat.cz/admin/file/tisoladegegori.pdfIn PDF document text
    • https://www.bosingels.nl/ckfinder/userfiles/files/1237564098.pdfIn PDF document text
    • https://ntct-dz.com/ckfinder/userfiles/files/67572660607.pdfIn PDF document text
    • http://asesoriagarpe.com/wp-content/plugins/formcraft/file-upload/server/content/files/16098520de88ba---sorizukanavizegarogowi.pdfIn PDF document text
    • http://kurskodkb.ru/page_edit/_samples/userfiles/files/65465472608.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_off00010169.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10169 19844 bytes
SHA-256: 6fb9a998e3a180ef40ae30d528d62012c29c86bef0dfa3488b1dc05b928ea3d2
font_01_sfnt_off0001352a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1352A 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00014d41.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x14D41 10260 bytes
SHA-256: 16bf406677dbff0cfd1eb4116d67dbf2c9001528b7563ce32000aaf8d0e8c09f

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