Malicious PDF — malware analysis report

Static analysis result for SHA-256 4ca09a1dbd3d2105…

MALICIOUS

PDF

85.3 KB Created: 2021-09-13 06:10:13 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-23
MD5: 36f4aa8b067ad10cdc05a46c5ed72d85 SHA-1: 5ef0c45fd80326dfe402b1e1f969a62357995fda SHA-256: 4ca09a1dbd3d21058bb2dca869a1dbe88fe65f26777925b682a83ea7719914f4
126 Risk Score

Malware Insights

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

The file was detected by ClamAV as Pdf.Phishing.Trojan and ML classifiers flagged it as malicious. It contains numerous embedded URLs, many pointing to PDF files on various domains, indicating a link farm. One heuristic specifically identified it as a 'PDF_SEO_DISPOSABLE_LINK_FARM' with a high number of distinct hosts and a redirector, suggesting a tactic to manipulate search engine results or distribute malicious content. The authoring application 'wkhtmltopdf' is unusual for a malicious PDF, but the overall structure and heuristic firings strongly suggest a malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9977

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://spalovnachemolak.sk/userfiles/file/puvejegapijifoma.pdf In PDF document text
    • https://aukshanya.promosing.com/alpha/ckfinder/userfiles/files/kidinelajiladuxep.pdfIn PDF document text
    • http://promocode.lu/userfiles/files/6174006081.pdfIn PDF document text
    • http://zenithmetals.com/files/xowadeda.pdfIn PDF document text
    • https://comillaspostgrado.es/userfiles/file/24909581982.pdfIn PDF document text
    • http://scherzerpc.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/25781799238.pdfIn PDF document text
    • http://1-champagne.com/blog_images/blog_/file/xetofojebibegobosukamox.pdfIn PDF document text
    • http://globalbizkorea.com/userData/board/file/27391164424.pdfIn PDF document text
    • https://vietnam-pump.com/userfiles/file/bonumumemupewewuripaza.pdfIn PDF document text
    • https://www.hungarianassociation.com/wp-content/plugins/formcraft/file-upload/server/content/files/161302c89ee91e---xozovugiwejubojunizeli.pdfIn PDF document text
    • http://parfumerieindex.nl/images/uploads/26869624538.pdfIn PDF document text
    • http://divorce-difficile.fr/userfiles/file/xosebojut.pdfIn PDF document text
    • https://dycmc.com/DATA/upload/files/202109081101233904.pdfIn PDF document text
    • http://esrafisek.com/images_upload/files/66999236758.pdfIn PDF document text
    • https://hbphoto.ca/resimler/files/7643113043.pdfIn PDF document text
    • http://vattucongtrinh.com/userfiles/file/33592800448.pdfIn PDF document text
    • http://orourkelawoffice.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/76062574854.pdfIn PDF document text
    • http://z-sinpro.com/upload/files/dalakusigifibof.pdfIn PDF document text
    • https://nbcmedia.vn/ckfinder/userfiles/files/rusisujef.pdfIn PDF document text
    • https://europartner2.pl/uploads/vipujidivipak.pdfIn PDF document text
    • https://alhurwallpaper.com/Files/files/30973671065.pdfIn PDF document text
    • http://yuhao-tech.com/userfiles/file/babitozokibipazup.pdfIn PDF document text
    • https://www.alertgy.com/wp-content/plugins/super-forms/uploads/php/files/987f74a13a6f5664dd9ffc3b452e47f1/zivelizorifuvurelafeme.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/1xuhb7AK25c/uplcv?utm_term=how+to+play+gta+5+on+android+phonePDF link annotation
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e8b9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE8B9 17620 bytes
SHA-256: 2b8125ba8e546f68101bbdba8475f2dee6bbd7828ad871f5b004690115d85f8f
font_01_sfnt_off000116d6.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x116D6 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00012eed.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12EED 10828 bytes
SHA-256: cced72212584d03b4d7dc5f9e4d65f09df412caaced44295759bebab35f4b3ec