Malicious PDF — malware analysis report

Static analysis result for SHA-256 a3a07bf4fd770853…

MALICIOUS

PDF

85.8 KB Created: 2021-09-16 02:56:13 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 5cc7e46cb6c95be6366d1337c97bd7a1 SHA-1: cd7eabeeda2fdef6e1074a4d38f7eb31d55bfdeb SHA-256: a3a07bf4fd77085305e575c521b2828e6ece9691685f938cf65cf95bd3599adf
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample was detected as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous embedded URLs, many of which point to potentially malicious PDF files, suggesting a link farm or redirection mechanism. The PDF_SEO_DISPOSABLE_LINK_FARM heuristic further supports this, indicating a tactic to obscure the true destination. While no scripts were explicitly extracted, the nature of the heuristics and the embedded URLs strongly suggest a phishing or malware distribution campaign, likely initiated via spearphishing attachment.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9991

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://taxiluzern.ch/khurasan/userfiles/files/874034874.pdf
    • https://bakotech.at/uploads/ckeditor/files/janemurasobu.pdf
    • https://kozlovka.mebel18.com/uploads/files/74548866979.pdf
    • http://www.omt.ntou.edu.tw/ckfinder/userfiles/files/lamovedakulepimefuv.pdf
    • http://zeci.nl/im/image/kubukurivadora.pdf
    • http://sujitonweb.com/userfiles/files/fijikoviwovelijudimumuwo.pdf
    • http://squash-fitness.cz/userfiles/file/23864745747.pdf
    • http://primeasset.hu/fileok/file/57975028311.pdf
    • https://alquimia.in/admin/fckeditor/editorfile/wivogepejumefekej.pdf
    • http://2girlstrippin.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613af636ca97d---32453392290.pdf
    • http://www.birapart.com/wp-content/plugins/formcraft/file-upload/server/content/files/16130c78e55e30---pebalevoxu.pdf
    • http://jakpaisanestate.com/images/upload/files/xixitakugoxa.pdf
    • http://www.childofafrica.org/media/userfiles/file/23041614350.pdf
    • https://kaowei.tw/image/files/20210904_120323.pdf
    • https://nstoplana.rs/ckfinder/userfiles/files/33773101482.pdf
    • http://elskenecologie.nl/files/65439548426.pdf
    • http://tnhmc.com/userfiles/file/22651391793.pdf
    • http://vonschickenconcord.com/uploads/files/78227107403.pdf
    • https://dlt-nkp.com/fileupload/file/13930571530.pdf
    • https://xn--nmqu14inmf.com/upload/files/99729217679.pdf
    • https://feedproxy.google.com/~r/skout/mBVl/~3/A3Ryygt5BCM/uplcv?utm_term=airdroid+similar+apps
    • 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_off0000ec4a.bin
3a16e13463cbdd37e71057ef9f3fa3c4ad7ac16718199555ed5a36f8c9ae2d7b		 pdf-font-stream PDF embedded font (sfnt) at offset 0xEC4A 10200 bytes
font_01_sfnt_off0001030f.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1		 pdf-font-stream PDF embedded font (sfnt) at offset 0x1030F 16792 bytes
font_02_sfnt_off00011b21.bin
00f3c07a812dbc91976f2d311e1043adef4ecac72802f5da7bf4b92b490ee75f		 pdf-font-stream PDF embedded font (sfnt) at offset 0x11B21 18132 bytes

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