Malicious PDF — malware analysis report

Static analysis result for SHA-256 b437f4a0dc6e19e0…

MALICIOUS

PDF

73.8 KB Created: 2021-09-14 09:54:07 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 6c5422b39efccdeb727adb137fd6a185 SHA-1: 81931b136f0b2715984e979c2cd65f8331f0bf26 SHA-256: b437f4a0dc6e19e07b0af3645f0d97a43c079cf4eda5359fa679a281faf93dcf
126 Risk Score

Malware Insights

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

The PDF was flagged by ML classifiers and ClamAV as malicious, with heuristics indicating it functions as a link farm on disposable hosting. The embedded URLs, despite some being marked benign, point towards a phishing or malware distribution scheme. The presence of PDF-specific exploits suggests an attempt to execute code upon opening.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9908

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 http://opt-russtd.ru/data_center/upload_pictures/file/kiripowonimovefemudineb.pdf
    • https://bselink.com/userfiles/file/dupebatimeseruto.pdf
    • http://ageofwonders.buka.ru/sadm_files/dagenigof.pdf
    • https://coevent.ru/upload/files/nadimefitulenevogegigu.pdf
    • http://smartmedicaleg.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613e760d30468---27944370611.pdf
    • http://dlevitin.ru/fck_editor_files/files/58578520268.pdf
    • http://simsvizag.com/contentimages/file/fegirapupaxamojijitup.pdf
    • http://tucholainfo.pl/userfiles/file/jofipavemebazuxesix.pdf
    • http://autoscuolauniversale.it/userfiles/files/budalux.pdf
    • http://imdad-egypt.com/userfiles/file/guruvur.pdf
    • http://samwha.com/upload/userfiles/file/89231090289.pdf
    • http://aadcnfgl.netsociality.com/upload/files/72922294019.pdf
    • https://familienbilstrup.dk/userfiles/file/pumeruwa.pdf
    • http://stluciachamber.org/uploadedImages/contentImg/file/87031147199.pdf
    • https://madeinstlucia.com/userfiles/files/nemixoga.pdf
    • https://taichielite.com/louis/taichi/ckfinder/userfiles/files/wuwaxijum.pdf
    • http://megamento.com/_UploadFile/Images/file/lasenipezedobuk.pdf
    • https://gopherscopes.com/userfiles/file/zowadakasumesuze.pdf
    • http://fisioterapiasuzzara.it/userfiles/files/bidakefogaj.pdf
    • http://theffirm.com/userfiles/file/40364080885.pdf
    • http://maekalocal.com/Maeka/UserFiles/File/74411471150.pdf
    • http://sofar-france.com/userfiles/file/51298908660.pdf
    • http://gshosnab.ru/userfiles/file/87097743692.pdf
    • https://www.projectorrentals.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613d726a42df6---nexuf.pdf
    • http://chiangmai-esc.net/user_img/files/tewerojepanixegopepate.pdf
    • http://papinchess.ru/userfiles/file/63595435803.pdf
    • https://feedproxy.google.com/~r/Uplcv/~3/DOqCt-cVA4I/uplcv?utm_term=rheumatoid+arthritis+and+massage+contraindications
    • 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_off0000be90.bin
eb6bffc8c2dbd1210782e6a064ab2e5eee3008d17d1b0b0dd854145871b5fc22		 pdf-font-stream PDF embedded font (sfnt) at offset 0xBE90 10916 bytes
font_01_sfnt_off0000d775.bin
f2df4d95727922e571c5428b13bd8473308e1d37ae6f638f21efb0546566aae3		 pdf-font-stream PDF embedded font (sfnt) at offset 0xD775 16076 bytes
font_02_sfnt_off000100d2.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1		 pdf-font-stream PDF embedded font (sfnt) at offset 0x100D2 16792 bytes

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