Malicious PDF — malware analysis report

Static analysis result for SHA-256 b4c8123700fa3683…

MALICIOUS

PDF

73.8 KB Created: 2021-09-13 01:34:29 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-23
MD5: 82435a07d2966d7ee9a3010f14fc1af3 SHA-1: 2689a534410b5a7863b0079ff5b092c705e73d26 SHA-256: b4c8123700fa36838f5dc803e2811adff600b45c517ea6bc09cab8418f54b430
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF document identified as malicious by ML classifiers and ClamAV. It contains numerous embedded URLs that form a link farm, with several pointing to compromised CMS upload storage. The document body is heavily obfuscated and unreadable, but the presence of external URIs and link farm heuristics suggests a phishing or SEO manipulation attempt. No scripts were extracted, but the overall structure indicates a malicious intent to redirect users to potentially harmful content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9968

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://medvor.ru/uplcv?utm_term=como+voltar+a+vers%C3%A3o+antiga+do+facebook+no+android PDF link annotation
    • http://rafaelokazakov.com/file/kulijo.pdfIn PDF document text
    • https://ddriu.hu/wp-content/plugins/super-forms/uploads/php/files/8ba915802e6f84b4fdbf1d3a73910681/borunemakavumoma.pdfIn PDF document text
    • https://bepxuyenviet.com/upload/files/27194590493.pdfIn PDF document text
    • http://drprdesaihospital.com/uploads/6118869447.pdfIn PDF document text
    • https://archcosmeticstudio.com.au/wp-content/plugins/super-forms/uploads/php/files/37a93665a1cf9e2b3a35c89d38f16a5d/fukomev.pdfIn PDF document text
    • http://domuran.pl/files/file/24435876409.pdfIn PDF document text
    • http://principessavencanice.com/wp-content/plugins/formcraft/file-upload/server/content/files/16139676ed58bd---lifubim.pdfIn PDF document text
    • http://wedooverseas.com/userfiles/file/32896756750.pdfIn PDF document text
    • http://krishikhabar.net/assets/ckfinder/core/connector/php/uploads/files/76424490388.pdfIn PDF document text
    • https://chambres-lannion.fr/userfiles/file/6197426250.pdfIn PDF document text
    • https://stellabakingcompany.com/wp-content/plugins/formcraft/file-upload/server/content/files/16130df365ae47---zanapitogijasus.pdfIn PDF document text
    • http://scantech3d.com/files/valufilavutejewigaze.pdfIn PDF document text
    • http://yasaitogo.com/uploads/files/73811749847.pdfIn PDF document text
    • http://ohdiabo.net/images/ckeditor/files/85364736194.pdfIn PDF document text
    • http://lineshare.net/upload/files/20210912160734.pdfIn PDF document text
    • https://elearning-chemistry.ro/userfiles/file/93904037274.pdfIn PDF document text
    • https://nodka.eu/ckeditor/ckfinder/userfiles/files/nulid.pdfIn PDF document text
    • https://www.institutvzdelavani.cz/files/mavemolezaburorozeroko.pdfIn PDF document text
    • http://elliptical-trainers.ru/ckfinder/userfiles/files/memulukedufigowudumela.pdfIn PDF document text
    • http://dolphinkorea.com/files/files/jilipipexugopab.pdfIn PDF document text
    • https://totalyoumovement.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613825ba57254---sudarunilovilufobevujexiv.pdfIn PDF document text
    • http://www.elmundodelapiscina.com/ckfinder/userfiles/files/82543356491.pdfIn PDF document text
    • http://vdavloeren.be/userfiles/files/zerudexor.pdfIn PDF document text
    • http://smsgurugram.com/miet/assets/files/49668724413.pdfIn 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://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_off0000b816.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB816 11412 bytes
SHA-256: 868d22059c7743e2e5f7f589b492b3defaa33eb7a2f29f88c5ee53004da1a4b2
font_01_sfnt_off0000d277.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD277 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000ea89.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEA89 18308 bytes
SHA-256: 6d0f45d09ef9e44007c5783d85d61b2c979d59aef709e2b322a77d6e5d68c041