Malicious PDF — malware analysis report

Static analysis result for SHA-256 181f5662ae859c24…

MALICIOUS

PDF

74.9 KB Created: 2021-09-18 04:31:41 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: b0a6e1ab185ba90ab808248895a4bae3 SHA-1: a64a8d6f4c3caec4fc16b6c6dd621e683c1790c0 SHA-256: 181f5662ae859c24004b5b4b97e3cf8f49ae4323888265bb62a86c4e84d0d670
156 Risk Score

Malware Insights

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

The PDF file was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, directing users to multiple external domains, some of which are hosted on compromised WordPress sites or disposable hosting. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for direct user reading but rather to host links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9980

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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://brazilairporttransfers.com/ckfinder/userfiles/files/58072123776.pdf In PDF document text
    • https://acrgroup.nl/userfiles/file/57149268869.pdfIn PDF document text
    • https://smartmedia.ro/app/webroot/files/userfiles/files/73185756203.pdfIn PDF document text
    • http://erulingua.hu/uploads/content_files/files/22873277211.pdfIn PDF document text
    • https://mertlakustika.cz/images/pages/file/fenav.pdfIn PDF document text
    • http://tele-klass.ru/i/upload/files/64027228794.pdfIn PDF document text
    • http://wx-bm.cn/upload/ckimg/files/202109101556208525.pdfIn PDF document text
    • https://primer-spb.ru/files/files/49628304094.pdfIn PDF document text
    • http://apexnepaltravel.com/userfiles/file/nanutera.pdfIn PDF document text
    • http://www.de.ruben.pl/ckfinder/userfiles/files/suduxojajemumiv.pdfIn PDF document text
    • http://ttworld.hu/uploads/content_files/files/rosajuloforuwulogodofaviv.pdfIn PDF document text
    • http://homeopathyhongkong.org/files/vifokidimejewegojodovo.pdfIn PDF document text
    • https://intelean.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613a44ff6ff4b---36412152349.pdfIn PDF document text
    • http://originalcheck.it/public/img_admin/file///86587978939.pdfIn PDF document text
    • https://journeywithmypet.com/ckfinder/userfiles/files/bokasopafegozil.pdfIn PDF document text
    • https://www.davinci.dk/wp-content/plugins/formcraft/file-upload/server/content/files/16142b3d693c45---pefakut.pdfIn PDF document text
    • http://vector-mebel.ru/uploads/files/5758553106.pdfIn PDF document text
    • http://www.teaterskolen-efteruddannelsen.dk/ckfinder/userfiles/files/wobukut.pdfIn PDF document text
    • http://weifong.tw/fckimages/file/tigidewotapezodigisusos.pdfIn PDF document text
    • http://cafehinglung.com/uploads/files/95376749901.pdfIn PDF document text
    • http://youzedu.com/ckimages/files/20210902055115621658.pdfIn PDF document text
    • http://jockmurray.com/wp-content/plugins/formcraft/file-upload/server/content/files/1614393d7b1b32---wekilevodumu.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/PmAiG5ZyT-k/uplcv?utm_term=group+chat+on+androidPDF 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_off0000c29d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC29D 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000dab4.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDAB4 10404 bytes
SHA-256: bab202029f5ab431f936d3fab0399d820941ae94f081d3a2f61e177506aee5f6
font_02_sfnt_off0000f229.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF229 17120 bytes
SHA-256: 11ac0d0f637e17764cd517342d709d3ea34bd6e0757f63ab324e856ebc0cd123