Malicious PDF — malware analysis report

Static analysis result for SHA-256 16535b5a1659f021…

MALICIOUS

PDF

71.7 KB Created: 2021-06-20 18:33:43 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-16
MD5: 68d1b8e5754b2b4620854b4081b68a33 SHA-1: ab8785051d0fdee533e3ab16e000207cba85c326 SHA-256: 16535b5a1659f02156242c6e0e0e01990f9921cc3b6e89e3080038f9d3157e6d
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript

The PDF file contains numerous links to external websites, many hosted on compromised WordPress installations, suggesting a link farm or phishing lure. The ML classifier and ClamAV detection strongly indicate malicious intent. The document body, though heavily obfuscated, contains references to 'Stardew Valley cheats' and 'wkhtmltopdf', indicating a deceptive lure to drive traffic to potentially malicious URLs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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://pistant.ru/uplcv?utm_term=stardew+valley+cheats PDF link annotation
    • http://inewbus.com/wp-content/plugins/super-forms/uploads/php/files/6acdtdjg84g78r00o2akjm0k42/55847923068.pdfIn PDF document text
    • https://www.hungarianassociation.com/wp-content/plugins/formcraft/file-upload/server/content/files/160777aed15325---7099931812.pdfIn PDF document text
    • http://xn----8sbpvg0afdbe.xn--p1ai/wp-content/plugins/super-forms/uploads/php/files/shh00lpjlm446in7e1ppg6b2u0/nimilokasulej.pdfIn PDF document text
    • https://www.sidertest.it/wp-content/plugins/formcraft/file-upload/server/content/files/1607688ed94582---61883547189.pdfIn PDF document text
    • https://forex-robo.org/wp-content/plugins/super-forms/uploads/php/files/43b71b2d6a7145946467bc23fb1da709/8843062161.pdfIn PDF document text
    • https://ambientltg.com/wp-content/plugins/super-forms/uploads/php/files/50a1953608f8e63ee95ac3a273c612c1/movatifidamamigazifexuxu.pdfIn PDF document text
    • https://precisionautoandac.com/wp-content/plugins/super-forms/uploads/php/files/94b30bead7c31bb5fc5c50766b7a6215/22002591912.pdfIn PDF document text
    • http://www.mkkdigital.pt/wp-content/plugins/formcraft/file-upload/server/content/files/160a2e7572006c---99003240926.pdfIn PDF document text
    • http://bazatalty.pl/wp-content/plugins/super-forms/uploads/php/files/1afb1f051dc212af792b76bb3fc4c6ad/40687962734.pdfIn PDF document text
    • http://lapenya.cat/imgjovesnaves/file/xibigeginoruwusovowerom.pdfIn PDF document text
    • http://www.ncstarim.com.tr/wp-content/plugins/super-forms/uploads/php/files/daj0mq61v85g3rmvkmqdfmjp33/rimebe.pdfIn PDF document text
    • http://amuseonline.com/absite/userfiles/file/46581998140.pdfIn PDF document text
    • http://www.julitolaschools.com/wp-content/plugins/formcraft/file-upload/server/content/files/160753f4d8f6a5---22749646907.pdfIn PDF document text
    • http://boissee.fr/userfiles/file/22031881490.pdfIn PDF document text
    • http://suportti.com/wp-content/plugins/formcraft/file-upload/server/content/files/16077a8ff0587a---18668535245.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000dbe5.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDBE5 5384 bytes
SHA-256: 10a0900822633d39a81f9715b7017106960422dad9ba5acf4efa80754164ced1
font_01_sfnt_off0000ee45.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEE45 10572 bytes
SHA-256: 797ff801327bfb2d937a5e02b6ac445ef9cc4579ab3e910e0b5ff6afbda73361