Malicious PDF — malware analysis report

Static analysis result for SHA-256 c15833f4b5596e66…

MALICIOUS

PDF

80.5 KB Created: 2021-09-18 07:24:25 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-26
MD5: 1768ca5955c2e530de34f2917fbae286 SHA-1: 3e1a2f6263021adba4f7e4fad39c6d5c3e968940 SHA-256: c15833f4b5596e6648a920dc3b4e31234bf242cda548198fb3c6bf48cb8bdc37
192 Risk Score

Malware Insights

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

The sample was detected by ClamAV as Pdf.Phishing.Trojan and flagged by an ML classifier, indicating malicious intent. It contains embedded JavaScript and a link farm pointing to compromised WordPress uploads and other disposable hosting, suggesting it's designed to redirect users to malicious content or phishing sites. The presence of urgency and callback lures further supports a phishing or scam-related attack pattern.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9975

Heuristics 9

  • 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.
  • 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.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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.santaterezinha.com.br/js/ckfinder/userfiles/files/demekuruvinabobew.pdf In PDF document text
    • http://plenar.hr/wp-content/plugins/formcraft/file-upload/server/content/files/161388f6dc0a0b---91220335113.pdfIn PDF document text
    • http://aiaato.com/FileData/ckfinder/files/20210902_6120572B59E4FEC5.pdfIn PDF document text
    • http://prodesign31.ru/wp-content/plugins/formcraft/file-upload/server/content/files/1613323e0d1c5b---42495481313.pdfIn PDF document text
    • http://climacom.eu/userfiles/files/18787808715.pdfIn PDF document text
    • https://academiapreprod.riportico.com/userfiles/files/54111304851.pdfIn PDF document text
    • https://maytinhdalat.vn/images/uploads/files/fabel.pdfIn PDF document text
    • https://gjbuyerbroker.com/userfiles/file/volotixepalebe.pdfIn PDF document text
    • http://beverly.kopanramen.com/uploads/files/40907669491.pdfIn PDF document text
    • http://artc-polymers.com/upload/images/files/bibatafexide.pdfIn PDF document text
    • https://www.aicsmindia.org/ckfinder/userfiles/files/nerexenofebu.pdfIn PDF document text
    • https://excore.hu/ckfinder/userfiles/files/10067245245.pdfIn PDF document text
    • http://abnicum.ru/files/file/44025222630.pdfIn PDF document text
    • https://sushixusa.com/userfiles/files/70204704855.pdfIn PDF document text
    • http://gro-felix.si/uploads/54537508232.pdfIn PDF document text
    • https://www.champagne-auge-dascier.com/ckfinder/userfiles/files/mixexezidakifafolumefula.pdfIn PDF document text
    • https://bbpartner.cz/userfiles/file/87532104056.pdfIn PDF document text
    • http://www.myhhsi.com/wp-content/plugins/super-forms/uploads/php/files/f9d7be0523180aa62dca1a875c4ed30c/3638726658.pdfIn PDF document text
    • https://russiancosta.ru/ckfinder/userfiles/files/65994296914.pdfIn PDF document text
    • http://skyrunarser.com/js/fckeditor/editor/filemanager/connectors/php/connector.php/upfiles/file/210902202134104272uleef6.pdfIn PDF document text
    • http://www.ddu-hk.cz/ckfinder/userfiles/files/tufisirasovudupale.pdfIn PDF document text
    • https://ohcsi.com/ckfinder/userfiles/files/80842783560.pdfIn PDF document text
    • http://soleilboo.com/images/uploads/files/xituzijuni.pdfIn PDF document text
    • https://taevlingar.se/images/pages/file/49974995907.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/Om9ozkHLxGw/uplcv?utm_term=hill+climb+racing+2+best+carPDF 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_off0000d7ef.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD7EF 10704 bytes
SHA-256: f6b3f03088f027131374472a31d1cf59ba0f9cf9ead960305184f36a20e9656c
font_01_sfnt_off0000f07a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF07A 17000 bytes
SHA-256: ae6389d6b52cf7a33d700fb78d7709a825a82a119a633a36f20287976345f11f
font_02_sfnt_off00011c3f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11C3F 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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