Malicious PDF — malware analysis report

Static analysis result for SHA-256 a9c63aff7d0b255c…

MALICIOUS

PDF

79.2 KB Created: 2021-09-16 07:29:08 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: cf0c8461ba1a72e7abd19ccbc0463ea6 SHA-1: 67e4c779e0e5c3bc5f677d6cc1da0005477855a2 SHA-256: a9c63aff7d0b255c116c6bf9c3b83496c445a775f49ead55a2c3b7a745f7d3a7
126 Risk Score

Malware Insights

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

The PDF file was flagged by multiple heuristics, including a critical ClamAV detection and an ML classifier, indicating malicious intent. The presence of numerous external URIs, many pointing to disposable hosting and configured as a link farm, suggests a phishing or malware distribution scheme. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, further obscuring its true purpose.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9978

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://pistant.ru/uplcv?utm_term=how+to+clear+cache+on+android+browser PDF link annotation
    • http://houtackers.nl/userfiles/file/88135672460.pdfIn PDF document text
    • http://abwlargo.com/uploads/files/21670056635.pdfIn PDF document text
    • https://doucetplasticsurgery.com/ckfinder/userfiles/files/xafevute.pdfIn PDF document text
    • http://schokozentrale.de/idata/55785934741.pdfIn PDF document text
    • http://westfallassociates.com/documents/file/59856403576.pdfIn PDF document text
    • http://hoclaixebinhthuan.com/upload/contentFile/file/vesolasexufupewilobimaw.pdfIn PDF document text
    • http://www.onekaddy.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613fb84990340---90211535395.pdfIn PDF document text
    • http://yokosohk.com/files/fckfiles/file/surisowuxi.pdfIn PDF document text
    • http://hanasushi6.com/uploads/files/memokenaxamovaw.pdfIn PDF document text
    • http://apart1day.ru/file/76629194895.pdfIn PDF document text
    • http://www.movingintofreedom.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613592cc6d53e---77798877035.pdfIn PDF document text
    • https://led7.ru/file/modadalulonarizidu.pdfIn PDF document text
    • http://96stone.ru/userfiles/file/82828950262.pdfIn PDF document text
    • http://markfarolaw.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/42470606375.pdfIn PDF document text
    • http://gesundheit-im-blog.de/userfiles/file/35315819121.pdfIn PDF document text
    • http://benevolo.it/userfiles/files/jarovuvetazo.pdfIn PDF document text
    • https://ksuskalology.com/images/file/88544125587.pdfIn PDF document text
    • http://kerekesvillszer.hu/UserFiles/file/fipajefesib.pdfIn PDF document text
    • https://partetesal.ir/data/file/menev.pdfIn PDF document text
    • https://zzhqhi.com/d/files/sivejotutadutogirowuxavaf.pdfIn PDF document text
    • https://livermore.com/wysiwygfiles/file/25814658810.pdfIn PDF document text
    • https://careerexpo.alljobsinliberia.com/ckfinder/userfiles/files/bezedixamomat.pdfIn PDF document text
    • http://gryfarmerskie.pl/pliki_wyswig/files/68231484645.pdfIn 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://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_off0000d2c9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD2C9 16896 bytes
SHA-256: ec0813068f752748498c2fb061e74785cad9a3d355f8cf968bab02d21d3e1656
font_01_sfnt_off0000fe39.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFE39 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00011650.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11650 10684 bytes
SHA-256: ef2acc38ffe8d092a16df605f804f3e142e93ab4abc1d3722c087dcbb72a765b

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