Malicious PDF — malware analysis report

Static analysis result for SHA-256 51f9a91ddf9fadb8…

MALICIOUS

PDF

87.3 KB Created: 2021-07-23 08:53:01 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-23
MD5: 2a7e148ed817dfcda83276d5d7373a1e SHA-1: d03afe2dfcc2027204f3415ec904e6eeb4d880ea SHA-256: 51f9a91ddf9fadb872459f1a6e73826e1f1fb236b66bcc39dd2d15cacaa7ba3e
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample was detected as malicious by multiple heuristics, including a high-confidence ML classifier and ClamAV. It functions as a link farm, directing users to numerous external PDF files hosted on various domains, many of which appear to be compromised or disposable. The presence of PDF_SEO_DISPOSABLE_LINK_FARM and PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM heuristics indicates a pattern of using such sites for malicious distribution. While no scripts were explicitly extracted, the PDF structure and the nature of the linked content suggest it's part of a phishing or malware distribution campaign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9991

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://instandee.com/Images_upload/files/dalabaxopataxosujomir.pdf In PDF document text
    • https://rescue.bg/wp-content/plugins/formcraft/file-upload/server/content/files/160c167fb4d1d3---16501006806.pdfIn PDF document text
    • https://isosklo.cz/uploads/jaziletinowufegel.pdfIn PDF document text
    • https://marksiegeldds.com/wp-content/plugins/super-forms/uploads/php/files/3cf80634f5e9e11fdbc71f699c540a74/34639590579.pdfIn PDF document text
    • http://automotiveenergy.cz/userfiles/file/12572222690.pdfIn PDF document text
    • http://cgt-fo-csc.fr/wp-content/plugins/formcraft/file-upload/server/content/files/160d39ca888d8b---fapukebefebenajogeka.pdfIn PDF document text
    • http://szpitalstrzelin.pl/userfiles/files/21261736582.pdfIn PDF document text
    • http://giustizianuova.it/userfiles/file/pefakaxofadaxapavofodo.pdfIn PDF document text
    • http://ophtalmic-overnight.fr/wp-content/plugins/formcraft/file-upload/server/content/files/1606f61b65d025---dugiranavojiw.pdfIn PDF document text
    • https://gamletaarnhuset.no/wp-content/plugins/formcraft/file-upload/server/content/files/160a8ce2b70433---temozetutabesujilufof.pdfIn PDF document text
    • http://www.awakohchang.com/image/upload/File/9886386041.pdfIn PDF document text
    • http://pvsystexperts.com/wp-content/plugins/super-forms/uploads/php/files/lgv6ma1rroqqbljgsprigovr42/99373164636.pdfIn PDF document text
    • https://advancedbusiness.co/wp-content/plugins/super-forms/uploads/php/files/694b0b773aede9b7d7f57657fde556e7/26088447478.pdfIn PDF document text
    • https://nuregio.de/wp-content/plugins/formcraft/file-upload/server/content/files/160bf2b15a5775---tagek.pdfIn PDF document text
    • http://showpalmedical.com/userfiles/fovidaw.pdfIn PDF document text
    • http://www.greenbriarpropmgmt.com/wp-content/plugins/super-forms/uploads/php/files/49dde3aa9b922b0c7c1127fd355b5c4a/mivasilepobadafujemo.pdfIn PDF document text
    • https://makemycake.gr/wp-content/plugins/super-forms/uploads/php/files/n0ln908pbqg3h773sjerjnorip/rorowokorivikukatoxewepe.pdfIn PDF document text
    • http://xtra360.net/campannas/file/jototasesavupofobafulubu.pdfIn PDF document text
    • https://cal.lighting/wp-content/plugins/super-forms/uploads/php/files/f9ceb625817e0c47d9bef29f0f8c5710/91994535936.pdfIn PDF document text
    • https://prikolnaya.com/wp-content/plugins/super-forms/uploads/php/files/7b65e113c4feed1ccb7c1f156c09b687/94748381460.pdfIn PDF document text
    • http://www.fotografoeventimilano.com/wp-content/plugins/formcraft/file-upload/server/content/files/1609850f7f00fd---jowiki.pdfIn PDF document text
    • http://nappsa.org/userfiles/file/dokubujovixuditapilofi.pdfIn PDF document text
    • https://www.infrascale.com/wp-content/plugins/super-forms/uploads/php/files/3b3610dfd6133a42afdf72af7d0c4c2b/50287266626.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/Om9ozkHLxGw/uplcv?utm_term=sample+letter+of+consent+to+use+propertyPDF 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_off0000f2dd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF2DD 16624 bytes
SHA-256: 79361cd71940e9c68f087b6451fd5fc4425f168e194370d6224bcf91c0609d3e
font_01_sfnt_off00011de3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11DE3 10836 bytes
SHA-256: 611a6d085c78356d9aaf667d5545edd9bee4ec4a386a4fc52a3342fbe3736af8
font_02_sfnt_off000136ef.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x136EF 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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