Malicious PDF — malware analysis report

Static analysis result for SHA-256 757dccbef57d97dc…

MALICIOUS

PDF

76.5 KB Created: 2021-09-19 13:47:33 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 2e7bebf39e8876b7fe1b4e1709004814 SHA-1: b5fd220a0403a13bf5578e99cce5bdb15fb42c92 SHA-256: 757dccbef57d97dc5bfb262b5478d930074c1e6c53e8ecddf8ec96ad33d3186a
126 Risk Score

Malware Insights

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

The PDF file was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, containing numerous links to disposable domains, with one prominent URL being https://catamma.ru/uplcv?utm_term=adb+in+mobile. The document body is heavily obfuscated and appears to be non-readable content generated by wkhtmltopdf, suggesting the primary malicious function is achieved through embedded links rather than document content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9963

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://catamma.ru/uplcv?utm_term=adb+in+mobile
    • http://watdoenwevandaag.nl/upload/6873250885.pdf
    • http://vetranhtuong.info/luutru/files/17473152879.pdf
    • http://www.absolutecateringla.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613ffff02beb8---ravav.pdf
    • http://4998horo.gmmwireless.com/contents/files/zoregezibevo.pdf
    • http://zhouzhuank.com/v15/Upload/file/20219122248114243.pdf
    • https://surupaceanu.ro/ckfinder/userfiles/files/42519817396.pdf
    • http://megatex-plast.ru/pub/file/38266943222.pdf
    • http://seanbittinger.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/75773842180.pdf
    • http://evola.it/userfiles/files/labilevisefiwofeviriwa.pdf
    • http://saga.diamonds/uploads/ckfinder/files/16189949609.pdf
    • https://artedelvalle.cl/gal/files/file/bajilevadosabakani.pdf
    • http://goldenteriyaki.com/uploads/files/toxukeku.pdf
    • http://patronusalapitvany.hu/public_html/upload/21748695247.pdf
    • http://mcutech.net/files/nijemirulemetib.pdf
    • http://studioagronomoserragiotto.eu/userfiles/files/wonopuzotasubido.pdf
    • https://homeaestheticsllc.com/wp-content/plugins/super-forms/uploads/php/files/3b33c85229502e074a2a0d331e549bd5/38531710288.pdf
    • http://studioarchperissinotto.eu/userfiles/files/zugevowexesiru.pdf
    • http://spy-military-labs.com/userfiles/file/26301212354.pdf
    • http://bapassamarinda.id/assets/ckfinder/core/connector/php/uploads/files/sirivugalepameforib.pdf
    • https://datenglagi.com/contents/files/24925966794.pdf
    • http://nktrading.qa/file/files/vuzonazaliwusu.pdf
    • http://standdominica.org/files/files/90130263765.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_off0000c980.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1		 pdf-font-stream PDF embedded font (sfnt) at offset 0xC980 16792 bytes
font_01_sfnt_off0000e197.bin
f145f1a4809d0fd3056b1e6a9ca6f7a312684b29b702316deaf88a8e49d3d97b		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE197 10000 bytes
font_02_sfnt_off0000f7a1.bin
7dc64104b1494493ea8a47cfcceef8fee26cde765010422522c84b9bfb1fda43		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF7A1 17640 bytes

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