Malicious PDF — malware analysis report

Static analysis result for SHA-256 855591782e2c755d…

MALICIOUS

PDF

86.9 KB Created: 2021-08-11 12:36:32 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-09-17
MD5: dbf604b5501f3c1f9ce12d28737987ee SHA-1: 111025d71096b9d1a2231bcb6dbd74889cde5d61 SHA-256: 855591782e2c755d580e6881e49d10263ca24b4141dd01c291cb54389be47f73
156 Risk Score

Malware Insights

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

The PDF contains a link farm pointing to numerous other PDF files hosted on compromised WordPress sites, indicating a phishing or malware distribution attempt. The ML classifier and ClamAV detection strongly suggest malicious intent. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, lacking direct user-facing content but serving as a vessel for the malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9931

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 http://perfectthesale.com/wp-content/plugins/formcraft/file-upload/server/content/files/16091bcbb7ca7a---58048273402.pdf In PDF document text
    • http://orrizon.ru/images/file/fekosofajigo.pdfIn PDF document text
    • http://maekuangudomthara.com/ckfinder/userfiles/files/18360471359.pdfIn PDF document text
    • http://tablica-nieruchomosci.pl/uploades/fckeditorfile/29803457078.pdfIn PDF document text
    • https://cristiandellavedova.com/wp-content/plugins/super-forms/uploads/php/files/j4q0iji8j7pmlf7n5rd8vn1d70/34018231034.pdfIn PDF document text
    • https://nomortiga.com/contents//files/24658229985.pdfIn PDF document text
    • https://dispomydeal.com/wp-content/plugins/super-forms/uploads/php/files/e3146ec83faba0eab0521a68dbc9b6af/fifogazonoxitimexupamamu.pdfIn PDF document text
    • http://turnyras.lt/Files/file/96443803061.pdfIn PDF document text
    • https://www.tai.gr/wp-content/plugins/formcraft/file-upload/server/content/files/16081694512912---zavunazumuzexev.pdfIn PDF document text
    • http://krishikhabar.net/assets/ckfinder/core/connector/php/uploads/files/72728990717.pdfIn PDF document text
    • http://topenglish.sk/app/webroot/gallery/files/xitem.pdfIn PDF document text
    • http://metabolit-plus.ru/files/file/72597402334.pdfIn PDF document text
    • http://traditionsradio.com/wp-content/plugins/super-forms/uploads/php/files/3n7j74l9ommbcr2d403sp12if5/95923740217.pdfIn PDF document text
    • https://www.coconutlodge.com/wp-content/plugins/formcraft/file-upload/server/content/files/16077b4b961b71---42447755988.pdfIn PDF document text
    • https://www.onestopnaturalstore.ca/wp-content/plugins/super-forms/uploads/php/files/rgkuoiucgrmtod9prmh1l59e2k/fevujupulev.pdfIn PDF document text
    • https://www.helmmsp.ca/wp-content/plugins/super-forms/uploads/php/files/ace4b1d5a9eb0ad3d14dbc986258dc3b/valopetusumuxisitogagomi.pdfIn PDF document text
    • http://nationalcoopadvisors.com/userfiles/files/movemoloboluwi.pdfIn PDF document text
    • https://www.hinogas.com/wp-content/plugins/super-forms/uploads/php/files/ke8aeu1b5s5cj2p6v9p3i5tarm/67796814557.pdfIn PDF document text
    • https://hydratrend.com/application/third_party/ckfinder/userfiles/files/5125702260.pdfIn PDF document text
    • https://studiogreenwich.ru/wp-content/plugins/super-forms/uploads/php/files/aa39b9621db140c2ab145dd2689d3550/80008032222.pdfIn PDF document text
    • http://www.cenlajobinator.com/siteuploads/editorimg/file/52099136939.pdfIn PDF document text
    • https://lysgaards.com/ckfinder/userfiles/files/bogakileb.pdfIn PDF document text
    • https://halobysciton.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608d2128b9285---wibixeliz.pdfIn PDF document text
    • http://highlandhighclassof1962.com/clients/c/c3/c330a44b04b080977bf299ea430a317d/File/67291066906.pdfIn PDF document text
    • http://sillajen.com/fckeditor/_upload/file/zezojezirivawob.pdfIn PDF document text
    • https://realimpacto.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/160d1d28f985f5---83269068838.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/6naE_Nh8_CY/uplcv?utm_term=ejercicios+de+palabras+agudas+llanas+y+esdrujulas+onlinePDF 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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d4da.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD4DA 11056 bytes
SHA-256: 6e2b4ef20f3d2a76cc374a7da3586da0f8e4f6cd7b5d19050ec3ee1381934287
font_01_sfnt_off0000ee33.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEE33 18980 bytes
SHA-256: c2c514660af4a9a044b672e36e98cb4e77d76f58b27e161b46aa3fcf35367a1b
font_02_sfnt_off00011dc9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11DC9 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_03_sfnt_off000135da.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x135DA 16312 bytes
SHA-256: 7d15b2d6d265aaca51dda18faee70a1b8fa9d95ed54cb111fb0895789092f9ae