Malicious PDF — malware analysis report

Static analysis result for SHA-256 821c21cb25686d9b…

MALICIOUS

PDF

70.5 KB Created: 2021-09-24 16:10:49 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 114b728d1ff8132073e05b4f74b77a16 SHA-1: cbaba42da85417fb8dc4f4473f6dd8a1102bae8b SHA-256: 821c21cb25686d9b1eecc5e604b73eb0b74f92ff79df8991af7406167a8a70ee
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, specifically as a phishing trojan. It contains numerous embedded URLs, many of which point to PDF files hosted on various domains, suggesting a link farm designed to redirect users. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' strongly indicates this malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9916

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 http://888chji.com/userfiles/files/73393522189.pdf
    • https://derfo.info/resimler/files/zaraxa.pdf
    • http://stinpo.com/ckfinder/userfiles/files/52200250190.pdf
    • https://boumqueur-edition.com/upload/fckeditor/file/76125355340.pdf
    • https://eprobatdz.com/ckfinder/userfiles/files/pagomuxavevuwimidagejad.pdf
    • http://mcdanielz.eu/files/file/94342601888.pdf
    • https://dijitalsanat.link/upload/files/ratola.pdf
    • http://alphasigmaoverseas.com/userfiles/file/82415339438.pdf
    • https://observatoire-omic.org/documents/file/xopiv.pdf
    • https://kaunas.cvzona.lt/resources/img/files/wubimunopedar.pdf
    • http://microcement.ua/userfiles/file/dogopawivufut.pdf
    • https://giriconsultancy.com/content_files/files/vakajerifotakube.pdf
    • https://drivetripper.com/userfiles2020/files/magene.pdf
    • https://bangvetthuong.com/luutru/files/87087183062.pdf
    • http://instit.ac/ckfinder/userfiles/files/87687025894.pdf
    • https://nmcs.ca/userfiles/files/nowuwagamaferagirotevo.pdf
    • http://foto-preiss.at/upload_files/files/57087606420.pdf
    • https://sanagustin.cl/files/gekaxagarapowirife.pdf
    • http://sokole-tps.pl/userfiles/file/67145017624.pdf
    • https://adverto.ee/userfiles/file/27605238546.pdf
    • http://wingmanresearch.com/userfiles/files/62012268187.pdf
    • http://lingvastar.z-i-g-z-a-g.com/userfiles/files/xexidukik.pdf
    • http://energyexcess.com/userfiles/file/85090431332.pdf
    • https://weyergans-hcc.lv/userfiles/file/rokikapewufe.pdf
    • https://carthink.org/wp-content/plugins/formcraft/file-upload/server/content/files/161423b3bcc60f---26810008768.pdf
    • http://assushop.com/userfiles/assushop.com/file/pisozuxik.pdf
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/fzgW7-mxBc0/uplcv?utm_term=i+know+better+meaning
    • 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_off0000b41b.bin
b8b72823c06aa4cf833778a7c4ddbc438c061d7b8fcc5e56f733731e50baf0a9		 pdf-font-stream PDF embedded font (sfnt) at offset 0xB41B 15732 bytes
font_01_sfnt_off0000dc2a.bin
b786b6e4c42d2458853e1e5c93cfecc7912dfcfcbe4bba9905535d139610da1d		 pdf-font-stream PDF embedded font (sfnt) at offset 0xDC2A 10504 bytes
font_02_sfnt_off0000f41a.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF41A 16792 bytes

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