Malicious PDF — malware analysis report

Static analysis result for SHA-256 21b1dc481684afd5…

MALICIOUS

PDF

80.7 KB Created: 2021-09-08 00:06:17 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: f2d694a3458033ac8c86d5e218372d08 SHA-1: 8874c24de5a3ff8e4e7eec80c0e7c9fab5aad1a5 SHA-256: 21b1dc481684afd5e2b9d7571f7a5a3a29ffbac287bd2994f61980c5eb717095
156 Risk Score

Malware Insights

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

The PDF file was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, with numerous external URIs pointing to potentially compromised WordPress upload storage and disposable hosting. The document body is heavily obfuscated and unreadable, suggesting it is not intended for direct user interaction but rather to host these malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9955

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://chcial.ru/uplcv?utm_term=mapa+metro+lisboa+pdf PDF link annotation
    • https://highfieldhousehotel.net/nbloom/fckuploads/file/dapedibunikodajumili.pdfIn PDF document text
    • http://www.thunderesp.com/ckfinder/ckfinder.htmlfiles/nuxalekepabadevisonezax.pdfIn PDF document text
    • http://zpb-maciejewski.pl/upload/fck/file/44694777592.pdfIn PDF document text
    • http://russkiivopros.com/images/FCKeditor/file/83611488782.pdfIn PDF document text
    • http://multi-accueil.fr/ressource/site-image/files/356002093.pdfIn PDF document text
    • https://corianderedmonton.com/ckfinder/userfiles/files/17607973335.pdfIn PDF document text
    • http://www.kinoimaging.nl/wp-content/plugins/formcraft/file-upload/server/content/files/160719698c7a97---4373882568.pdfIn PDF document text
    • http://plncse.hu/php_data/file/piwefewogugudovejunir.pdfIn PDF document text
    • http://www.virtualaid.eu/wp-content/plugins/formcraft/file-upload/server/content/files/1606d3b195fb7e---54342496749.pdfIn PDF document text
    • http://sun-tes.ru/files/file/xixijozasodufufunanem.pdfIn PDF document text
    • http://lungtransplantopen.com/clients/d/de/de7cc03d42bda6b8b84c8ac9728529bb/File/vadixem.pdfIn PDF document text
    • http://aptchasers.com/FCKeditor/userfiles/file/nitibo.pdfIn PDF document text
    • https://agmatbaa.com/upload/files/buweko.pdfIn PDF document text
    • http://sgpeo.pl/users/file/retum.pdfIn PDF document text
    • http://szrealty.net/uploadpic/2021-5/file/2021051615574473499.pdfIn PDF document text
    • https://alfa-clining.ru/wp-content/plugins/super-forms/uploads/php/files/c79b2b3674734e88b45dcfb6df75f031/puzizato.pdfIn PDF document text
    • https://frennphotography.com/wp-content/plugins/formcraft/file-upload/server/content/files/160a8a5c257600---xujodom.pdfIn PDF document text
    • http://poongdung.com/FileData/ckfinder/files/20210621_91C708B4AA11DBC8.pdfIn PDF document text
    • http://allg-gyn.ch/userfiles/file/xamodaroludaguvigovexuz.pdfIn PDF document text
    • https://csom.cz/wp-content/plugins/super-forms/uploads/php/files/e3c8a7bdd3df9f833d90ca460f385f41/45796167537.pdfIn PDF document text
    • http://premiumresourcing.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606fff76c0691---voxagimozarikufubalew.pdfIn PDF document text
    • http://noithatsah.com/webroot/img/files/tubunuwekiwuwab.pdfIn PDF document text
    • https://www.oneirishrover.com/wp-content/plugins/super-forms/uploads/php/files/b95da3461b88956b84567dbd4c12f41e/gapadaboja.pdfIn PDF document text
    • https://retrofitoman.com/ckfinder/userfiles/files/lapifoduxupatose.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_off0000d15f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD15F 10688 bytes
SHA-256: 67ca9928befec02b51ed84e17e7384f2887f0a67db765b93483c3b54dd5c6596
font_01_sfnt_off0000e9a3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE9A3 19636 bytes
SHA-256: db1d16dcdeb2ed6a5b9d269f45287f0b8f50c95e7aeb8f09c05e2d53a28ba26a
font_02_sfnt_off00011c32.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11C32 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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