Malicious PDF — malware analysis report

Static analysis result for SHA-256 c5832a33eaa2c8df…

MALICIOUS

PDF

90.0 KB Created: 2021-09-15 22:51:46 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-27
MD5: 0091af9fe75bf5c390b1e31c60fcc8c7 SHA-1: b4aa88a927de9b04e849a2b554483dee2620bdf4 SHA-256: c5832a33eaa2c8df70e926259f4e7c19ec5fec7b102ada9fd92ad87f83554c69
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample was detected by ClamAV as Pdf.Phishing.Trojan and flagged by an ML classifier, indicating malicious intent. It contains numerous external URIs, including one pointing to 'synerhu.ru', suggesting it functions as a link farm or phishing lure. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' further supports this, indicating a pattern of using disposable hosting for a large number of links. No scripts were extracted, but the PDF structure itself is leveraged for malicious redirection.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9822

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 https://synerhu.ru/uplcv?utm_term=kyrie+eleison+partitura+pdf PDF link annotation
    • http://euro-ex.com/images/blog/file/72615507226.pdfIn PDF document text
    • http://upservice.expert/admin/ckfinder/userfiles/files/jorejuza.pdfIn PDF document text
    • https://butyfarm.mm520.net/userfiles/files/15230903145.pdfIn PDF document text
    • http://usairsprings.com/userfiles/file/dilotogopukusafijov.pdfIn PDF document text
    • https://brunoamaranti.it/wp-content/plugins/super-forms/uploads/php/files/0tl5okkr8ldp7vk61boqj1aa57/54509610043.pdfIn PDF document text
    • http://dissanna.com/temp/fckeditor/file/xutetozimazini.pdfIn PDF document text
    • http://villa-carlshorst.de/sites/default/files/file/10550007545.pdfIn PDF document text
    • http://www.lircai.com/web/inline/file/89251428868.pdfIn PDF document text
    • http://matchedtubes.de/userfiles/file/wupol.pdfIn PDF document text
    • http://maekuangudomthara.com/ckfinder/userfiles/files/puxelologosutog.pdfIn PDF document text
    • https://certifiedmoversinc.com/wp-content/plugins/super-forms/uploads/php/files/dfc9bcb8a87afc67a4db44fe2ec66189/93754983075.pdfIn PDF document text
    • http://sorokolaw.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/26861476465.pdfIn PDF document text
    • http://mgocsm.in/userfiles/file/23530901350.pdfIn PDF document text
    • http://fujieshubao.com/zk/UploadFile/file/2021090503481773499.pdfIn PDF document text
    • https://fuoriscena.eu/file/giwenaxaxobe.pdfIn PDF document text
    • http://yavuzselimvakfi.org/resimler/site/files/vajivejepugube.pdfIn PDF document text
    • http://tuecpa.com/file_media/file_image/file/43974841622.pdfIn PDF document text
    • http://www.moyekolodin.com/files/47383252299.pdfIn PDF document text
    • http://detskaoptika.cz/ckfinder/userfiles/files/gizufemototuf.pdfIn PDF document text
    • https://nbtele.com/en/cache/fck_files/file/tazosa.pdfIn PDF document text
    • http://vongtaygiay.net/media/ftp/file/fafumoweboramidujataxo.pdfIn PDF document text
    • http://magnumprint.ru/upload/files/25094347578.pdfIn PDF document text
    • http://htwy.com/upload/file/71222414326.pdfIn PDF document text
    • http://auto-spec.ca/fck/file/tifukitijapenedaxedew.pdfIn PDF document text
    • http://perilatomsk.ru/ckfinder/userfiles/files/somoraxodojifidonu.pdfIn PDF document text
    • http://ipai-bg.eu/img/file/gazugugarovatoxow.pdfIn PDF document text
    • http://homesunshinepharma.com/upload/files/katajufatifivilizidap.pdfIn PDF document text
    • 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_off0000f1a8.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF1A8 10696 bytes
SHA-256: 63feb49801857cb5db7f0fef0f3e7eb62190114717a13827b837d3d81a215996
font_01_sfnt_off00010a53.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10A53 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00012265.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12265 20836 bytes
SHA-256: a8615deadf95e1d60eec93af7b12e67876b1fb603188b9bba8f2f43c2cc90357