Malicious PDF — malware analysis report

Static analysis result for SHA-256 f6639149335f6abe…

MALICIOUS

PDF

75.8 KB Created: 2021-06-23 11:10:47 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-11
MD5: 194531559ce39312d5abaad8440337a0 SHA-1: f869b34d1cabb431fab5840982868d5f0bbfc46d SHA-256: f6639149335f6abe71f048cd8238ac5ac51fadebac53f07fa3df5f3f3eeeeb88
156 Risk Score

Malware Insights

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

The PDF file was flagged by ClamAV as Pdf.Phishing.Trojan and an ML classifier indicated a high probability of maliciousness. It contains numerous links, many hosted on compromised WordPress sites or disposable domains, suggesting a link farm used for phishing or malware distribution. The document body, though heavily obfuscated, contains references to 'English grammar in use pdf book' and 'wkhtmltopdf', indicating a lure to disguise the malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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://drafthe.ru/uplcv?utm_term=english+grammar+in+use+pdf+book PDF link annotation
    • http://lhdrum.com/User_File/UpFile/file/20210602004954_bmltYXRpbGlkZXNhdG9rdXhlYm9iZW5l.pdfIn PDF document text
    • http://aksaaydinlatma.com/img/editor/image/file/1050375231.pdfIn PDF document text
    • http://www.look4job.gr/images/_user_na/file/rigetedamifagakimoxake.pdfIn PDF document text
    • https://him-home.ru/wp-content/plugins/super-forms/uploads/php/files/1caaab86595766bb57f739f80be23282/nafozinu.pdfIn PDF document text
    • http://e-pisanie-prac.pl/famprojekt_z_serwera/images/file/zokowojip.pdfIn PDF document text
    • http://decamiones.com/userfiles/file/35600681437.pdfIn PDF document text
    • https://asaptransfers.co.uk/wp-content/plugins/super-forms/uploads/php/files/b212gdcita8kot1l7ehbhg2gt0/xezanipadeget.pdfIn PDF document text
    • https://www.drserapkagan.com/wp-content/plugins/super-forms/uploads/php/files/koreml2fhpptfkenflmvb9je46/nogozixis.pdfIn PDF document text
    • https://ludifrance.fr/userfiles/file/20895902824.pdfIn PDF document text
    • http://uat.ideadunes.com/projects/ideadunes-portfolio-site/wp-content/plugins/formcraft/file-upload/server/content/files/1606ed247db790---60601118349.pdfIn PDF document text
    • http://www.maoles.com/wp-content/plugins/formcraft/file-upload/server/content/files/16078e46974763---nukuj.pdfIn PDF document text
    • https://www.helpforbusymums.com/wp-content/plugins/super-forms/uploads/php/files/3c4baa991fe68fce037874708e6e5863/90251140450.pdfIn PDF document text
    • http://bellsazshihtzu.com/clients/878694/File/31883179332.pdfIn PDF document text
    • https://nhaban24h.com.vn/wp-content/plugins/super-forms/uploads/php/files/qeqrhbjdrp26nkhkkfi7tg0oto/mataradujo.pdfIn PDF document text
    • http://rethabise.co.za/wp-content/plugins/formcraft/file-upload/server/content/files/16098773317a20---jamavenudadanegofex.pdfIn PDF document text
    • http://bindashnews.com/userfiles/file/2211933360.pdfIn PDF document text
    • http://for-rent-antwerp.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607827e34d8c7---gowonoguxibujulid.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000ea44.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEA44 5616 bytes
SHA-256: 75ac1a73be3d6a18d02eeeacbba4da86a6c322a7543d4fae39ce15c3ded8b928
font_01_sfnt_off0000fd32.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFD32 10816 bytes
SHA-256: 78f5d9103a01dbf03f163354aac0480c607b46e94c6bf751a2653ed27715e7e9