Malicious PDF — malware analysis report

Static analysis result for SHA-256 31a6b51249fcd516…

MALICIOUS

PDF

73.6 KB Created: 2021-09-05 13:05:30 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-21
MD5: a493543ac566ac43f35e39683a7abf13 SHA-1: c81df9459c12fd9b565bd816e889f525293f1f09 SHA-256: 31a6b51249fcd51644087d01fab820a80d70b9e46e216b1d79559dce020765ce
96 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF contains a link farm pointing to multiple compromised CMS upload directories, which in turn host other PDF files. The ML classifier strongly indicates maliciousness. This pattern suggests the document is part of a phishing or malware distribution campaign, using a network of compromised sites to host and redirect to malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9981

Heuristics 5

  • 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://billedbutikken.dk/articlefiles/file/80198739850.pdf In PDF document text
    • https://stradatextiles.com/upload/ckfinder/files/18499399519.pdfIn PDF document text
    • http://global-gypsum.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608a943ef145f---wipobajedovolaraxaza.pdfIn PDF document text
    • http://dangkyidol.com/wp-content/plugins/super-forms/uploads/php/files/p48fq9khgeqjdgu8tc0m60blu3/sizana.pdfIn PDF document text
    • http://abnicum.com/files/file/93337161569.pdfIn PDF document text
    • http://jagatjyotischool.org/jagatjyotischool/userfiles/file/8947336399.pdfIn PDF document text
    • http://interwork.sk/userfiles/file/167247360.pdfIn PDF document text
    • http://gibisch.biz/files/files/79398413340.pdfIn PDF document text
    • http://brukbet.com/user_images/file/41243994174.pdfIn PDF document text
    • https://upbfassadenbau.com/upload/file/24615764377.pdfIn PDF document text
    • http://kraljicabih.com/wp-content/plugins/formcraft/file-upload/server/content/files/160a5f96c65076---77487297095.pdfIn PDF document text
    • http://tachikawa-derma.biz/ckfinder/userfiles/files/xumevinakadikabinotojifot.pdfIn PDF document text
    • https://drainscovers.com/wp-content/plugins/super-forms/uploads/php/files/4c61e1827615549818f788a90a4cd17e/91052633594.pdfIn PDF document text
    • https://audreyheselmans.com/_files/file/wozubogofojadaxizinam.pdfIn PDF document text
    • https://robertmatzuzi-massagetherapist.co.uk/wp-content/plugins/formcraft/file-upload/server/content/files/1612b2823a3974---rodufedikaromazenafad.pdfIn PDF document text
    • http://ahchala.com/img/file/salabetosot.pdfIn PDF document text
    • http://www.cpnatacao.pt/backoffice/ckfinder/userfiles/files/37054012255.pdfIn PDF document text
    • http://huichem.com/ckfinder/userfiles/files/xilagamezodazotovu.pdfIn PDF document text
    • https://groupburuemas2.com/contents//files/movarojuwuw.pdfIn PDF document text
    • http://akkoryazilim.com/userfiles/file/14039411959.pdfIn PDF document text
    • http://kapelski.pl/userfiles/file/mesitejelapufik.pdfIn PDF document text
    • https://yar-net.ru/userfiles/file/30918568510.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/FevRqgeaUVY/uplcv?utm_term=recruitment+process+in+hrm+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_off0000bed9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBED9 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000d6eb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD6EB 16116 bytes
SHA-256: d3143b7a853d93e8bbfe82d3946323455bde103fd93cda6cb03555fa722a5b14
font_02_sfnt_off0000fffd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFFFD 10820 bytes
SHA-256: 81b0f5ed438a6b19bf2cbfa88b515c78ca29770a52f911b7e2dd6bb724e3f27e