Malicious PDF — malware analysis report

Static analysis result for SHA-256 4f636a9c052d94b6…

MALICIOUS

PDF

96.8 KB Created: 2021-06-29 04:33:26 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-09-29
MD5: 823dbd9c401c05614bfeb0d79c224e9a SHA-1: 8ef1c25b9c5438d52775a7a53afae833df3690d6 SHA-256: 4f636a9c052d94b6cb1bf282e4321b06b82130ffc993dd740a261c482bca8dad
156 Risk Score

Malware Insights

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

The PDF was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, directing users to multiple distinct hosts, many of which appear to be compromised WordPress installations. The document body is heavily obfuscated and unreadable, suggesting an attempt to hide its true purpose, which is likely to lure users to malicious sites for credential harvesting or further payload delivery.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9936

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://dungcuruamui.com/wp-content/plugins/super-forms/uploads/php/files/4mckmog3tmhok7h5p3ekcpvlbs/31472575721.pdf In PDF document text
    • https://phoenixknights.co.uk/wp-content/plugins/super-forms/uploads/php/files/dd0dc1f755e2eb553b2b5584bcdd1ba7/62675127418.pdfIn PDF document text
    • http://mirembeestate.co.ug/wp-content/plugins/formcraft/file-upload/server/content/files/1607fdf4b126d7---4375711895.pdfIn PDF document text
    • http://eltonltd.ru/sites/default/files/uploads/64016162338.pdfIn PDF document text
    • http://www.nuricomuvakfi.org/wp-content/plugins/super-forms/uploads/php/files/j6v5a6jsen3hjvrus3smjqv4i4/29933819005.pdfIn PDF document text
    • https://brokenspoke.com/wp-content/plugins/super-forms/uploads/php/files/3f4e1aa9b0f6643e7bdd2a6c79273bbb/53295519583.pdfIn PDF document text
    • http://www.sempresaude.net/wp-content/plugins/formcraft/file-upload/server/content/files/16095ae3fe1d57---luderezikobufix.pdfIn PDF document text
    • http://studiotecnicobonoli.com/userfiles/files/tugobezerutibi.pdfIn PDF document text
    • http://dom-nenilovo.ru/wp-content/plugins/super-forms/uploads/php/files/7bed810f18851baa416976ebecd0fc31/80765985757.pdfIn PDF document text
    • http://3bbb.fr/ckeditor/upload/files/81425563576.pdfIn PDF document text
    • https://www.diktu.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608f734776859---xesuwaperumezim.pdfIn PDF document text
    • https://siyata.co.il/wp-content/plugins/formcraft/file-upload/server/content/files/160c05ad948d7d---68358321690.pdfIn PDF document text
    • http://grani-tonkogo-mira.ru/wp-content/plugins/super-forms/uploads/php/files/4ef5734b9f113a6f9ed7140f289d17f5/kigos.pdfIn PDF document text
    • https://kalatranslation.co.uk/wp-content/plugins/super-forms/uploads/php/files/vqs9vaudetcpaomidrsv6akmth/suxepedejibil.pdfIn PDF document text
    • http://www.samlab.com.tr/wp-content/plugins/super-forms/uploads/php/files/9iipm4tin21nekqhhij7qhj81v/27632938584.pdfIn PDF document text
    • https://dentinale.eu/wp-content/plugins/super-forms/uploads/php/files/fe08e17d0823e62064fbcaed2cb0a7f7/82038979532.pdfIn PDF document text
    • http://noithattamphuong.com/upload/files/waxuxam.pdfIn PDF document text
    • http://altaprecision.com/userfiles/file/37034612891.pdfIn PDF document text
    • http://iideree.org/wp-content/plugins/formcraft/file-upload/server/content/files/160c99a6c4662c---57675795459.pdfIn PDF document text
    • https://hospvetcentral.pt/site/upload/file/2300184759.pdfIn PDF document text
    • http://plncse.hu/php_data/file/60765246734.pdfIn PDF document text
    • https://iominneapolis.com/wp-content/plugins/super-forms/uploads/php/files/ad589e375c53f7d98f7598b281e9c66b/bigafodud.pdfIn PDF document text
    • https://argumentua.com/i/file/21243161995.pdfIn PDF document text
    • https://directorvincentchow.com/fck_filemanager_upload/file/xugedovijuganotaneluvon.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/1KS0DP0cxss/uplcv?utm_term=thematic+vocabulary+listPDF 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_off000110a7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x110A7 20928 bytes
SHA-256: 35a9001340b6d6cbc1e0b4db3954489d4cf2b141076bfaa9f38ab8c8d809dd93
font_01_sfnt_off0001455c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1455C 10776 bytes
SHA-256: 725853bb829090e11ffe1f251865386696475f4be84d1140ec3ccce44a9396ed
font_02_sfnt_off00015e40.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x15E40 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1