Malicious PDF — malware analysis report

Static analysis result for SHA-256 833f7726a55a51d3…

MALICIOUS

PDF

68.5 KB Created: 2021-09-30 10:18:04 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-25
MD5: 72640ead10fd429f7219519f14b0cc32 SHA-1: ecafcd32e58ed110b5917d228aedbcf091eeb368 SHA-256: 833f7726a55a51d3b898290fe2078909c194d316bf3ec10da544a448bf6c1ac4
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF was flagged by ClamAV as Pdf.Phishing.Trojan and an ML classifier indicated a high probability of maliciousness. It contains numerous embedded URLs, many pointing to compromised WordPress sites or disposable hosting, suggesting a link farm designed to lure users to external sites. The presence of PDF_SEO_DISPOSABLE_LINK_FARM and PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM heuristics further supports this. While no scripts were extracted, the overall structure and URL patterns are indicative of a phishing or malware distribution attempt.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

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://krisoc.ru/uplcv?utm_term=gta+v2+apk PDF link annotation
    • https://worldkelo.com/wp-content/plugins/super-forms/uploads/php/files/d968dbd9ff149fe526ea7161a7dce591/86608884012.pdfIn PDF document text
    • https://habibitours.net/ckfinder/userfiles/files/38616989864.pdfIn PDF document text
    • http://thanhnhomdinhhinh.net/uploads/files/nimemiputaxizise.pdfIn PDF document text
    • https://na-nule.ru/wp-content/plugins/super-forms/uploads/php/files/40rkki2nkpt31g03a1f81ta0b7/nebiwolin.pdfIn PDF document text
    • http://xn--80aadcnaeutgftohcogh8i8dsc.xn--p1ai/pict/file/tifesopubofinejoz.pdfIn PDF document text
    • http://cataga.de/beta/files/file/xezoxudefapa.pdfIn PDF document text
    • https://tebra.si/userfiles/file/mosefaxutapu.pdfIn PDF document text
    • http://www.impactit.in/ckfinder/userfiles/files/tilizofop.pdfIn PDF document text
    • http://limpiasol.com/wp-content/plugins/formcraft/file-upload/server/content/files/16144644986bad---61211219398.pdfIn PDF document text
    • https://artemishosp-em.tw/uploads/files/202109240322593439.pdfIn PDF document text
    • http://mixmarketing.vn/upload/fck/file/39393296088.pdfIn PDF document text
    • https://atolab.it/wp-content/plugins/super-forms/uploads/php/files/bf5db9ab484c4e51a5791a6329fb5c73/zebupem.pdfIn PDF document text
    • http://mistral-paints.cz/userfiles/files/nisiwopimumomojopijetoj.pdfIn PDF document text
    • https://frontivo.ro/userfiles/file/vujufolikaxazomirev.pdfIn PDF document text
    • http://falerisztika.hu/tmp/sejelovidumotilene.pdfIn PDF document text
    • https://aksukartela.com/images_upload/files/kinopobeterelu.pdfIn PDF document text
    • http://swancentive.com/cote_dor_import/admin/ckfinder/userfiles/files/gudalomezizogod.pdfIn PDF document text
    • https://qpshouse.com/upload/image/file/22803508264.pdfIn PDF document text
    • https://dynasty888.com/image/files/20210912_025553.pdfIn PDF document text
    • http://7m-shop.com/userfiles/file/18811890984.pdfIn PDF document text
    • https://westcoastmovers.ca/wp-content/plugins/super-forms/uploads/php/files/fluav605dgrr1atmdo027ffatb/56740571891.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_off0000ad5c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xAD5C 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000c572.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC572 9800 bytes
SHA-256: 984c20793f602c8b9ae1533c9039125d26e322b5c3fd20a94425cea280460b3d
font_02_sfnt_off0000db26.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDB26 16380 bytes
SHA-256: 6c09e8a7859e11cd5ae04b3c4b0e691f5d39ff49e592e484e9844c553b37afc1