Malicious PDF — malware analysis report

Static analysis result for SHA-256 c3d8b9de346e627e…

MALICIOUS

PDF

76.1 KB Created: 2021-09-14 06:14:18 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-14
MD5: 7f9e26f79f948b0f7b60808a1c28a679 SHA-1: 4193b0e42695fef806a571ea38298f33fe4bcc03 SHA-256: c3d8b9de346e627e0a5f1559da7fc088b47fb97b897159eec8d76024ac361daf
96 Risk Score

Malware Insights

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

The PDF file contains a link farm with numerous URLs pointing to other PDF documents, many hosted on compromised CMS upload directories. This suggests a tactic to manipulate search engine results or distribute further malicious content. The ML classifier strongly indicated maliciousness, and the structure aligns with link farm distribution techniques.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9980

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://www.huaikrachaohospital.go.th/assets/global/lib/ckfinder/userfiles/files/12342667123.pdf In PDF document text
    • http://bilagroup.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613c294c377fe---rulifexok.pdfIn PDF document text
    • http://pyramidplaster.com/file_media/file_image/file/13271682143.pdfIn PDF document text
    • http://szigmetal.hu/editor_up/670739452.pdfIn PDF document text
    • http://vtracauto.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613b7b985a24b---89389744129.pdfIn PDF document text
    • http://banglenhospital.com/UserFiles/File/92571598485.pdfIn PDF document text
    • https://currenwatch.myhost360.cn/file/upload/files/09-02-10-57-04-28.pdfIn PDF document text
    • https://jiu-hang.com/upfiles/editor/files/79867436060.pdfIn PDF document text
    • http://witnesstherealist.com/wp-content/plugins/super-forms/uploads/php/files/99d85a1949b07b2e84b6d55f788a206c/40483127580.pdfIn PDF document text
    • https://festivalecolo.ca/wp-content/plugins/formcraft/file-upload/server/content/files/16134a93eb1091---gijufinulavovew.pdfIn PDF document text
    • https://carthink.org/wp-content/plugins/formcraft/file-upload/server/content/files/16132669346ef0---kogiv.pdfIn PDF document text
    • http://iccjsc.vn/images/uploads/files/liwufonixumisilap.pdfIn PDF document text
    • http://studiogaleazzo.eu/userfiles/files/41146532283.pdfIn PDF document text
    • https://www.higher-energy-trampolineclub.com/wp-content/plugins/formcraft/file-upload/server/content/files/161347203a6706---16860373669.pdfIn PDF document text
    • http://duoctruongxuan.vn/userfiles/image/file/kogiropizurowuma.pdfIn PDF document text
    • http://www.rebranded.tv/wp-content/plugins/formcraft/file-upload/server/content/files/16137684919024---54137994026.pdfIn PDF document text
    • https://sklep-pinokio.pl/web/uploads/files/pagugixevanidokojumusuge.pdfIn PDF document text
    • http://www.ks-klinika.ru/ckfinder/userfiles/files/katoxopamaxexunok.pdfIn PDF document text
    • https://livre-art.com/ckfinder/userfiles/files/1395139820.pdfIn PDF document text
    • http://turar-mussin.com/userfiles/File/70434899236.pdfIn PDF document text
    • http://pscworld.eu/ckfinder/userfiles/files/nevuloz.pdfIn PDF document text
    • http://de.ruben.pl/ckfinder/userfiles/files/24848202972.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/3CAf4wW3hvY/uplcv?utm_term=graph+of+sine+squaredPDF 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_off0000c375.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC375 10736 bytes
SHA-256: 8c87d910c4a4744e4204f5591bafe06715892eefbba13876babecf9deda92829
font_01_sfnt_off0000dbce.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDBCE 18028 bytes
SHA-256: 59c5173e9b56a1d7c5a227d25e7b826283cb0d482819530d31de099107e26f6a
font_02_sfnt_off00010abc.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10ABC 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1