Malicious PDF — malware analysis report

Static analysis result for SHA-256 c841873cdc1afa41…

MALICIOUS

PDF

86.5 KB Created: 2021-09-04 16:55:12 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-05
MD5: d5228c983dd88e12756fe9b341696ddf SHA-1: 4161fa576d59b09f78b64d1d2c57db5f10cab915 SHA-256: c841873cdc1afa416f7f7d7d53c5433f2b86bcaa26ce3688f28d85ea39bd1f93
164 Risk Score

Malware Insights

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

The PDF contains embedded JavaScript, a common technique for exploiting PDF vulnerabilities to execute arbitrary code. Several heuristics indicate the presence of malicious content, including a link farm pointing to compromised WordPress uploads and a high ML classifier score. The embedded JavaScript likely attempts to download and execute a second-stage payload from one of the identified URLs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9974

Heuristics 7

  • 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.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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://ski-valloire.com/ckfinder/userfiles/files/93734440315.pdf In PDF document text
    • https://jdbailbonds.com/wp-content/plugins/super-forms/uploads/php/files/79654cdcfbdfec098df87f9d48c0a7c4/rutinuxoraz.pdfIn PDF document text
    • http://principessavencanice.com/wp-content/plugins/formcraft/file-upload/server/content/files/160bfd4166eb44---rederuxunatikerutumivulex.pdfIn PDF document text
    • https://hondaotohaiphong.vn/upload/files/sexuku.pdfIn PDF document text
    • http://www.xpresswedding.com/wp-content/plugins/formcraft/file-upload/server/content/files/160af69ab1dd93---gigowolinamiwaroxovor.pdfIn PDF document text
    • https://em.heephong.org/ethnicminorities/cmsadmin/ckfinder/files/78952402345.pdfIn PDF document text
    • http://calisnt.com/uploads/files/lanatupusufezuwi.pdfIn PDF document text
    • http://braintradingbcn.com/wp-content/plugins/super-forms/uploads/php/files/a39b4199d3f69a2fe35faf661a686204/24813023792.pdfIn PDF document text
    • https://matskaren.se/anvandarbilder/203/files/bikuz.pdfIn PDF document text
    • http://staging.impactredevelopment.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607c1fb94ffdd---ketewadinafegewuw.pdfIn PDF document text
    • http://kronospan-mofa.hu/editor_up/fenabivotinezajukobagovos.pdfIn PDF document text
    • http://insk.ru/img/userfiles/file/guvojuvatukudejeg.pdfIn PDF document text
    • http://www.jhannahs.com/wp-content/plugins/formcraft/file-upload/server/content/files/16070a852f3aac---3503240099.pdfIn PDF document text
    • http://altelaw.com/uploads/image/file/nibutosugamimipo.pdfIn PDF document text
    • http://adria-ex.com/images/blog//file/82144678470.pdfIn PDF document text
    • http://mfahk.com/upload/files/36043935711.pdfIn PDF document text
    • http://learnazia.com/fck/imagesfile/fejuvov.pdfIn PDF document text
    • http://leaguengn.com/userfiles/file///18362701533.pdfIn PDF document text
    • https://shop-ecobati.com/medias/upload/files/rifamapiw.pdfIn PDF document text
    • https://www.caesarstravel.com/wp-content/plugins/formcraft/file-upload/server/content/files/160770addb6d27---48880484371.pdfIn PDF document text
    • https://www.scilights.com/wp-content/plugins/super-forms/uploads/php/files/f2d0c08c6b76a668fcbd6eab46e0eff8/kilabuzaluvuzizabutunerad.pdfIn PDF document text
    • http://test.uebersetzungen-nesselberger.de/wp-content/plugins/formcraft/file-upload/server/content/files/16078f10582248---32260404001.pdfIn PDF document text
    • http://inewbus.com/wp-content/plugins/super-forms/uploads/php/files/94jtbrbkr03ft5cgdj74hv7il7/mofemiwewokaxibetanivifol.pdfIn PDF document text
    • https://i-chat.tw/js/ckfinder/userfiles/files/fuvixoninokapabizo.pdfIn PDF document text
    • http://cleannshieldflorida.com/wp-content/plugins/super-forms/uploads/php/files/7b195f7fe238855ca821cbc122e835a5/tafiz.pdfIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/1KS0DP0cxss/uplcv?utm_term=pdf+splitsen+acrobat+readerPDF 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_off0000ee51.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEE51 10752 bytes
SHA-256: 31afea9ad81c515ad49f5e99ae2a250512074679f27773dc43c2de74864ad44d
font_01_sfnt_off000106e9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x106E9 17368 bytes
SHA-256: 3c79115a484700fe9055c6acf5599a7a178fba649ca7c782a7718c5e50f22645
font_02_sfnt_off00013408.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13408 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1