Malicious PDF — malware analysis report

Static analysis result for SHA-256 79837ab0865f7b7d…

MALICIOUS

PDF

82.9 KB Created: 2021-09-19 00:55:20 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: cfb23b1737137ed8825ab554a99894c9 SHA-1: 7e1d8f015b809b28209413dcfcf8a113e2e203f4 SHA-256: 79837ab0865f7b7d8d93dee333e32eeb935616b8e84d3bad6c33f73d6a75fdbd
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF document was flagged by multiple heuristics, including ML classifiers and ClamAV, indicating malicious intent. It contains numerous embedded URLs, with one specifically noted as a redirector with UTM parameters, suggesting a phishing or malware distribution campaign. The presence of PDF_SEO_DISPOSABLE_LINK_FARM heuristic further supports the idea of a link farm designed to obscure the final malicious destination.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9974

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://krisoc.ru/uplcv?utm_term=sat+practice+test+7+pdf
    • http://www.painters-restaurant.com/userfiles/file/bivoxuzupovesepabasi.pdf
    • http://oryginalnedekoracje.pl/userfiles/file/mepiri.pdf
    • http://jmk.kr/ckfinder/userfiles/files/93972057043.pdf
    • https://mysilo.com/upload/ckfinder/files/2399404472.pdf
    • https://nabsangram.com/userfiles/file/69665768600.pdf
    • http://sumisaedu.com/FileData/ckfinder/files/20210905_B8E8FF57C1FB96C7.pdf
    • http://memsports.com.br/admin/libs/ckeditor/ckfinder/files/84488009101.pdf
    • https://ptogel2.com/contents/files/34482125006.pdf
    • http://gryfarmerskie.pl/pliki_wyswig/files/fisawerudawan.pdf
    • http://hnc2.com/userfiles/file/faniriratizutesemoseso.pdf
    • http://change4best.ru/upload/file/65275849745.pdf
    • http://hissekurban.com/resimler/files/jamosawoxedusiw.pdf
    • https://transport-vehicules.fr/userfiles/file/vagupinifiwilalalijol.pdf
    • https://sdhouse.info/ckfinder/userfiles/files/lomuliduzajadupizirej.pdf
    • http://laconchigliacasevacanze.it/userfiles/files/20566918330.pdf
    • https://betsin.org/userfiles/files/nutuxasakulatatoduduwi.pdf
    • http://frederickfollows.co.uk/wp-content/plugins/formcraft/file-upload/server/content/files/1613390ac53e77---repiluzoje.pdf
    • http://bulmarconsult.com/files/jusosorejagatavar.pdf
    • https://huaku3c.tw/uploads/files/202109081848375575.pdf
    • http://bike-aholic.com/UserFiles/file/78354099762.pdf
    • https://lerong.vn/wp-content/plugins/super-forms/uploads/php/files/f8fcde53f33aaa9e2a268b750c3abe00/12246202002.pdf
    • http://challendor.com/fckeditor/upload/file/pekomijep.pdf
    • https://fivetc.vn/uploads/files/75613046293.pdf
    • http://yingtailong.com/upload/file/210912050209545498e4omeyzcgjjz.pdf
    • http://geomanteia.com/userfiles/files/74478349689.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://dejavu.sourceforge.net
    • http://dejavu.sourceforge.net/wiki/index.php/License

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000dc2f.bin
36fe3973da5cec32a1778030346866d42ab0de18d20b7abcb256dc799072d03a		 pdf-font-stream PDF embedded font (sfnt) at offset 0xDC2F 19124 bytes
font_01_sfnt_off00010dc5.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1		 pdf-font-stream PDF embedded font (sfnt) at offset 0x10DC5 16792 bytes
font_02_sfnt_off000125dc.bin
9b5b1150d8e0a454341b513048161788683549e8767617349b256fc0418034ff		 pdf-font-stream PDF embedded font (sfnt) at offset 0x125DC 10468 bytes

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