Malicious PDF — malware analysis report

Static analysis result for SHA-256 d856d2abdee76552…

MALICIOUS

PDF

77.5 KB Created: 2021-10-12 06:29:11 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-23
MD5: 77bc4310a37b3d89873166c1ac74fc4f SHA-1: aa3502a03b19167275ce2b5a1df283f951923f32 SHA-256: d856d2abdee76552362fc9f8e1d0730ef1afe841974f6d6fccebff1b8cc1b8a4
96 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF contains a large number of embedded URLs, many of which point to other PDF files hosted on various domains. Several heuristics indicate this is a link farm, with some links pointing to compromised CMS upload directories. The ML classifier strongly flagged this PDF as malicious, suggesting it is part of a campaign to distribute malicious content or manipulate search engine results.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

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 https://almuhja.ps/ckfinder/userfiles/files/bipapogirobol.pdf In PDF document text
    • http://dailythang.com/userfiles/files/kogavu.pdfIn PDF document text
    • https://hilanguage-com-tw.triangle-design.com/files/jatoxazejiwexaxegojex.pdfIn PDF document text
    • http://schokoladenbrunnen.de/idata/79500780718.pdfIn PDF document text
    • http://themultifold.com/wp-content/plugins/super-forms/uploads/php/files/hkf4kcv07c9cdnlqkkn8hblqd6/zuvomazatizijekaxakude.pdfIn PDF document text
    • https://inchirieriavioane.ro/wp-content/plugins/formcraft/file-upload/server/content/files/1614fbb7e59bfc---kanoxawofobupan.pdfIn PDF document text
    • http://ahchala.com/img/file/lelanuzejep.pdfIn PDF document text
    • https://reha.bg/content/upload/file/kalinumixe.pdfIn PDF document text
    • http://kodemari.info/data/files/40035846296.pdfIn PDF document text
    • https://www.vigo.co.za/wp-content/plugins/formcraft/file-upload/server/content/files/16142565fea747---kotudemipukiw.pdfIn PDF document text
    • https://casaalu.com/luutru/files/30658368590.pdfIn PDF document text
    • https://hum639hb2-hh38.com/contents/files/vifosamiwabaxevabijan.pdfIn PDF document text
    • http://jindi2010.com/uploadfile/files/folujilu.pdfIn PDF document text
    • http://leicesterbiketec.com/userfiles/file/17656795128.pdfIn PDF document text
    • https://macleanpinesdrivingschool.com.au/wp-content/plugins/super-forms/uploads/php/files/0d531ae4385131bd1eceed743cf257cb/39929438804.pdfIn PDF document text
    • http://seoulgreeter.com/userData/board/file/papetisoduka.pdfIn PDF document text
    • https://www.assofmt.org/ckfinder/userfiles/files/28552188705.pdfIn PDF document text
    • http://sanxuatbanthinghiem.org/app/webroot/uploads/files/43740750817.pdfIn PDF document text
    • http://inica.org/files/file///niwexerixewanod.pdfIn PDF document text
    • https://vernadoc.com/wp-content/plugins/super-forms/uploads/php/files/aa2c52a00e177e619eb3bf177a5a109d/gigimojudowosuj.pdfIn PDF document text
    • https://luckyfood.itweald.com/uploads/files/6164c0c0df297.pdfIn PDF document text
    • https://limsurdua.com/contents/files/84847561531.pdfIn PDF document text
    • https://sanmuabancongty.vn/images/content/files/sisujeradutiwilajapuki.pdfIn PDF document text
    • https://aokman-drive.com/d/files/tenufaraligugowarevafejas.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Gsjc/~3/HKUGBsJGI0E/uplcv?utm_term=go+your+own+way+high+school+musicalPDF 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_off0000c9ca.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC9CA 10784 bytes
SHA-256: 10e816f84a988d5d930fae8c5daad6f8ca072569dfc5456662691e4e30d5348f
font_01_sfnt_off0000e278.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE278 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000fa8a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFA8A 17608 bytes
SHA-256: c19791494d13e29196de9808af4104f24aed842ebfc18d2044806c7dfab166d0