Malicious PDF — malware analysis report

Static analysis result for SHA-256 81dd3749329e7c1b…

MALICIOUS

PDF

94.5 KB Created: 2021-09-04 17:34:11 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-23
MD5: 8a73db67ca3cd9777ec60af47993e336 SHA-1: be53394707954215b345b8f923db06a1912a603c SHA-256: 81dd3749329e7c1b2af227842f87567b93be65aaa8042e8bcd5617c3c13e982e
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. It contains a large number of embedded URLs, many of which point to compromised or disposable hosting, suggesting a link farm designed to distribute malicious content or phish for credentials. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, providing no direct user-facing text but containing structural elements indicative of a malicious PDF.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9897

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 http://cl-metalparts.com/d/files/nesikobavon.pdf In PDF document text
    • https://www.aserspa.net/wp-content/plugins/super-forms/uploads/php/files/m2jnkdmgccmkfuf6dgc3bf6845/55244244521.pdfIn PDF document text
    • http://cbstav.cz/file/43100081764.pdfIn PDF document text
    • http://rwdwebwebdesign.com/img-aim/files/56184110072.pdfIn PDF document text
    • https://durgabas.coop.np/ckfinder/userfiles/files/81236344780.pdfIn PDF document text
    • https://chamsocmuihong.com/wp-content/plugins/super-forms/uploads/php/files/epgnsur5ie495g595l22ms4dm4/34918645103.pdfIn PDF document text
    • http://eduomania.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608aacbb2f5e8---lowivemeludixigizekufib.pdfIn PDF document text
    • http://pavcargo.ru/wp-content/plugins/super-forms/uploads/php/files/50003d8d36f07597705b6f0d0030ba96/vifewalorabumarebajili.pdfIn PDF document text
    • https://www.brightfieldbusinesshub.co.uk/wp-content/plugins/super-forms/uploads/php/files/er3qudvr7odefh84f2k1cgpetk/22658110367.pdfIn PDF document text
    • https://stpatswatertown.org/ckfinder/userfiles/files/42915370925.pdfIn PDF document text
    • https://amartzon.store/wp-content/plugins/super-forms/uploads/php/files/a669231783fbe913d4a2f52c0338116f/72535980867.pdfIn PDF document text
    • http://www.onekaddy.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607bd2833d71a---mudidatikuwisemut.pdfIn PDF document text
    • https://artedelvalle.cl/gal/files/file/57524455999.pdfIn PDF document text
    • https://suemsas.com/wp-content/plugins/super-forms/uploads/php/files/dpvp364uitpvb7t1q1utok2n51/83841047097.pdfIn PDF document text
    • http://www.gradur.ba/wp-content/plugins/formcraft/file-upload/server/content/files/160ac409cd3e99---joretevotuvofulilunewove.pdfIn PDF document text
    • https://nucamsa.es/userfiles/files/95290901812.pdfIn PDF document text
    • http://guowangcable.com/d/files/54534888313.pdfIn PDF document text
    • https://cualuoihoanmy.com/uploads/userfiles/file/vunukutulobof.pdfIn PDF document text
    • https://massagetheory.ca/wp-content/plugins/super-forms/uploads/php/files/dd264f3361e368f905ae599d28e27c74/39312476740.pdfIn PDF document text
    • https://best-turbos.com/wp-content/plugins/super-forms/uploads/php/files/7464e920b5e84e756528d70d6e1eb7c8/lifajelokigim.pdfIn PDF document text
    • https://daiichigroup.net/uploads/news_file/dexinaxonukenobezusimepi.pdfIn PDF document text
    • http://www.timtransportes.com/home/wp-content/plugins/formcraft/file-upload/server/content/files/1607b24c00c820---9593207138.pdfIn PDF document text
    • https://gionggiacam.com/ckfinder/userfiles/files/buwifajubiduratejanabez.pdfIn PDF document text
    • http://www.mostex.sk/files/articles/file/25547966815.pdfIn PDF document text
    • http://bazatalty.pl/wp-content/plugins/super-forms/uploads/php/files/8492a70bf0b727bd377ddff9b67a2660/gesaki.pdfIn PDF document text
    • https://alrukn.co/userfiles/files/nibofujexatigikowoze.pdfIn PDF document text
    • http://www.kevimotor-rock.hu/files/files/55534349584.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/PmAiG5ZyT-k/uplcv?utm_term=manual+monitor+cardiaco+speedo+80621g0evnp1PDF 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_off000100de.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x100DE 11688 bytes
SHA-256: 7eb72c33de4c638e922128a4d871fc73b560ca2869636b6ec56a10d0217a6e15
font_01_sfnt_off00011c8c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11C8C 21368 bytes
SHA-256: 3bee17a9a4d973182e359a2b5931ea1b110c0f42f7e9f3946da1b4c9f5e6929d
font_02_sfnt_off000153a7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x153A7 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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