Malicious PDF — malware analysis report

Static analysis result for SHA-256 81370c351b3c6154…

MALICIOUS

PDF

74.0 KB Created: 2021-10-05 00:04:21 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-23
MD5: a0ed28d36db946dab39a211307348473 SHA-1: 3d31758c6f53e981eca736b6fa0a82661473eee8 SHA-256: 81370c351b3c6154a2fa28ad962e5cfe4a579a02d22bf3199f70e872e6cc92cd
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains numerous links to external PDF files hosted on various domains, many of which appear to be part of a link farm designed to manipulate search engine results or distribute malicious content. The ClamAV detection and ML classifier strongly indicate malicious intent, likely related to phishing or malware delivery. Although no scripts were explicitly extracted, the PDF structure and embedded URIs suggest it's designed to redirect users to potentially harmful content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9947

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 http://dptour.net/bot/ckfinder/uf/files/fukilar.pdf In PDF document text
    • https://bepxuyenviet.com/upload/files/26015822435.pdfIn PDF document text
    • http://seosanhrd.com/userfiles/file/22369385890.pdfIn PDF document text
    • http://businessvaluationapp.com/fck_files/file/64817922625.pdfIn PDF document text
    • https://bipalisdemo.dashindonesia.com/userfiles/files/lamojofejigax.pdfIn PDF document text
    • http://baharev76.ru/userfiles/file/foredidi.pdfIn PDF document text
    • https://www.cifphosteleriayturismo.es/ckfinder/userfiles/files/5829978179.pdfIn PDF document text
    • https://xn--80aesyq.xn--p1ai/files/file/gesenezoxupuxor.pdfIn PDF document text
    • https://rhythmcprandfirstaid.com/wp-content/plugins/super-forms/uploads/php/files/06b24ef50ebee9c365a301d2f97de2e9/gojesor.pdfIn PDF document text
    • http://nelly-design.ru/upload/files/66703818793.pdfIn PDF document text
    • http://queuemanagementsystems.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613667c110c39---76230436059.pdfIn PDF document text
    • http://pc580.cn/upload_fck/file/2021-10-4/20211004050144817874.pdfIn PDF document text
    • http://avstralianature.ru/ckfinder/userfiles/files/vaxoniredapa.pdfIn PDF document text
    • https://rmdschoolandcollege.com/wp-content/plugins/super-forms/uploads/php/files/fa294d916876c682cd14c26779e0d7c6/98172732877.pdfIn PDF document text
    • http://108shiva.com/userfiles/file/In PDF document text
    • https://likeevent.it/writable/public/userfiles/file/jezorokalej.pdfIn PDF document text
    • https://imagebuzz.net/ckfinder/userfiles/files/bamosuv.pdfIn PDF document text
    • http://allamericannursing.com/userfiles/file/12756453981.pdfIn PDF document text
    • http://ttccid.com/userfiles/file/50393628567.pdfIn PDF document text
    • https://asiatravel.kg/wp-content/plugins/super-forms/uploads/php/files/58c071c62a267bb2a9e75d184e7ed682/47588623598.pdfIn PDF document text
    • http://www.amedna.com/userfiles/files/bulusaganotulapoli.pdfIn PDF document text
    • http://bugskin.org/userfiles/file/sanagawawu.pdfIn PDF document text
    • http://topas.lt/userfiles/file/jivemumebuka.pdfIn PDF document text
    • https://goldfieldssanddrags.com.au/ckfinder/userfiles/files/25441945802.pdfIn PDF document text
    • https://etest.vn/app/webroot/uploads/files/sonevuponisokane.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/PmAiG5ZyT-k/uplcv?utm_term=ugc+net+2020+previous+year+question+paperPDF 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_off0000bc55.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBC55 17220 bytes
SHA-256: 58ee267509e305e0e5e676230bcdd84a694332a77188227b23107223329c37ee
font_01_sfnt_off0000e837.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE837 11180 bytes
SHA-256: a0647b4ad82c2b208fbf40037a9e4ca796678e3e166c2a15942402e159da7ce8
font_02_sfnt_off00010251.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10251 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1