Malicious PDF — malware analysis report

Static analysis result for SHA-256 81733dbd3b776f78…

MALICIOUS

PDF

81.5 KB Created: 2021-09-14 06:11:14 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-31
MD5: 80718b62e9f647ac191b2275d68aeb8f SHA-1: 41c50a0f3fc1246ce6d3cabc623ac3c61e68db75 SHA-256: 81733dbd3b776f7802d0663e18cfe6a22cddcd5e9c7584ac7bb71cc79a6ed5b7
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF file flagged by ClamAV as Pdf.Phishing.Trojan and by an ML classifier as malicious. It contains numerous embedded URLs, many of which point to disposable hosting and are part of a link farm, indicating a phishing or malware distribution attempt. The wkhtmltopdf authoring application suggests it may have been generated programmatically to host these links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9846

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://huntic.ru/uplcv?utm_term=send+files+android+to+ios PDF link annotation
    • http://harposwebdesign.nl/app/webroot/files/userfiles/files/81950607664.pdfIn PDF document text
    • https://studiecarriere.it/uploads/file/jopegilumolagidurosixejew.pdfIn PDF document text
    • https://leosservices.com/userfiles/file/bedusatajovuk.pdfIn PDF document text
    • https://bacninhonline.com/webroot/img/files/rubofu.pdfIn PDF document text
    • http://njuhome.pl/ckfinder/userfiles/files/40300594976.pdfIn PDF document text
    • http://fence-alarm.com/userfiles/files/20761641012.pdfIn PDF document text
    • https://pnp-studio.com/fckeditorfiles/file/77099275766.pdfIn PDF document text
    • https://delphin-restaurant.com/ckfinder/upload/files/kajozix.pdfIn PDF document text
    • https://ketgate.eu/wp-content/plugins/super-forms/uploads/php/files/7157c9323d10bcf2f5e34e8abc47e3e6/birekotik.pdfIn PDF document text
    • https://bientannamhuy.com/wp-content/uploads/files/58942540174.pdfIn PDF document text
    • http://deurwater.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613c7f73c64d6---31739477713.pdfIn PDF document text
    • http://harringtonassociateslaw.com/Test/JabzMedicalBillingService/userfiles/file/zirobeno.pdfIn PDF document text
    • http://jjw-led.com/userfiles/file/jubinedov.pdfIn PDF document text
    • http://mdbim.pl/ubezpiecz/obrazy/file/fokugimogolizerapezowop.pdfIn PDF document text
    • http://nedirajtebosnu.net/userfiles/file/navode.pdfIn PDF document text
    • https://rimi.sk/userfiles/file/vokukakidel.pdfIn PDF document text
    • http://xn--80aadq3ae7aa5k.xn--p1ai/upload/file/gagaduxazejonimaf.pdfIn PDF document text
    • http://dison.cn/filespath/files/20210909024948.pdfIn PDF document text
    • https://study-abroad-travel.com/ckfinder/userfiles/file/17737309802.pdfIn PDF document text
    • https://niboparis.com/upload/fckeditor/files/bamituvepapirijigozufida.pdfIn PDF document text
    • http://a2kat.ru/userfiles/file/xowapa.pdfIn PDF document text
    • http://dbcasagayathottam.org/assets/uploads/cms_images/files/falefebotexuj.pdfIn PDF document text
    • http://noavarservice.com/ckfinder/userfiles/files/71994912546.pdfIn PDF document text
    • https://aradmissions.com/ci/userfiles/files/duwel.pdfIn PDF document text
    • http://draftingfloorplan.com/ckfinder/userfiles/files/kijefi.pdfIn PDF document text
    • http://tks-forever.com/upload/2021/09/02/file/wonerixedabas.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_off0000d76a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD76A 10424 bytes
SHA-256: 850d4cafdd03399769ca191e8307e5b0e4c665369a8d6611f0bfb717ea250958
font_01_sfnt_off0000ef25.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEF25 19024 bytes
SHA-256: 9eae081d8b05855dd40d3283b97f664966c0cb17b55f71b28eddc449587abfd2
font_02_sfnt_off00012076.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12076 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1