Malicious PDF — malware analysis report

Static analysis result for SHA-256 51c5eca62d686848…

MALICIOUS

PDF

86.8 KB Created: 2021-08-18 15:01:50 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-31
MD5: 8a08e5cec3c3836df5c6f604176dbcb3 SHA-1: 5b545a38e27df6798e3d63d36506fbe8404040fe SHA-256: 51c5eca62d686848c1a031642679e1748134274bd9afed7593fa7a269ab8fae6
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF file was identified as malicious by ML classifiers and ClamAV, specifically flagged as a phishing trojan. Heuristics indicate it functions as a link farm, with numerous embedded URLs pointing to potentially compromised websites or disposable hosting. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for direct user reading but rather as a vehicle for these links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9987

Heuristics 6

  • 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.
  • 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://fundreamz.com/ckfinder/userfiles/files/nuxezed.pdf In PDF document text
    • http://bizwd.com/wp-content/plugins/formcraft/file-upload/server/content/files/160bc95eb0660c---podepuxati.pdfIn PDF document text
    • https://rsun.pro/admin/ckfinder/userfiles/files/50484016037.pdfIn PDF document text
    • https://discoverapartmentsforrent.com/wp-content/plugins/super-forms/uploads/php/files/6f8dc49d47cc8e8ee5b6bdf2b125b669/nisudamanasagetagudojure.pdfIn PDF document text
    • http://www.farparts.cl/wp-content/plugins/formcraft/file-upload/server/content/files/160dad9cee4aca---widirijisip.pdfIn PDF document text
    • http://art-ball.net/files/file/rujadevezexakedurodeli.pdfIn PDF document text
    • https://liniagdanskzydowo.pl/files/dosafipuwokarajote.pdfIn PDF document text
    • http://princeworldwide.com/multimedia/userfiles/file/13852590666.pdfIn PDF document text
    • http://novo-foto.ru/ckfinder/userfiles/files/4765091990.pdfIn PDF document text
    • https://iamluno.com/wp-content/plugins/formcraft/file-upload/server/content/files/160ae266bc36aa---kolan.pdfIn PDF document text
    • http://www.gamylai.vn/uploads/files/wutetaxariwanedevavoziv.pdfIn PDF document text
    • http://rjt1.org/upload/files/55203807947.pdfIn PDF document text
    • http://osrclass1967.com/clients/8/84/84e84eb3bb32f45446e669e24fea3ebc/File/56928080626.pdfIn PDF document text
    • http://music-saikung.com/ckfinder/userfiles/files/30005823627.pdfIn PDF document text
    • http://coming-c.com/userfiles/file/takirizu.pdfIn PDF document text
    • http://kaztelcom.kz/ckfinder/userfiles/files/19028647895.pdfIn PDF document text
    • https://www.mii.net/wp-content/plugins/super-forms/uploads/php/files/1b6f4b3abbf3fded8763b9ce7fbe100c/80202249350.pdfIn PDF document text
    • http://intechsol.kz/wp-content/plugins/formcraft/file-upload/server/content/files/16073b9b61422e---76174486942.pdfIn PDF document text
    • https://www.winsum.frl/ckfinder/userfiles/files/simijogewofegujarutep.pdfIn PDF document text
    • http://vegasoft.hr/wp-content/plugins/formcraft/file-upload/server/content/files/160cdd50bc3f93---puxitokewej.pdfIn PDF document text
    • https://suemsas.com/wp-content/plugins/super-forms/uploads/php/files/in4efk9v9adojcahjkon0dgdu3/86733684745.pdfIn PDF document text
    • http://angeladaniel.eu/uploads/files/rubawateselot.pdfIn PDF document text
    • https://bodymason.com/user_uploads/files/71838201251.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/DOqCt-cVA4I/uplcv?utm_term=what+is+social+ethics+pdfPDF 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_off0000f339.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF339 10504 bytes
SHA-256: 994de6edffe6f41aa023c762f703a0826e60195cbf5f1a1e233446a771d61c4a
font_01_sfnt_off00010b4a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10B4A 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0001235c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1235C 16124 bytes
SHA-256: 22d3644bc3f5103a90b901a523d63b060f345994359f203dc82e32effeacd5ed

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