Malicious PDF — malware analysis report

Static analysis result for SHA-256 50b5553075cba4ba…

MALICIOUS

PDF

80.3 KB Created: 2021-09-04 13:18:19 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 8a03a76914f67eea4d67307444e8ae99 SHA-1: bdc4edd7c3a7df5ebcf8d54fcb3fc7029a57db02 SHA-256: 50b5553075cba4ba5a97481a544eed8bdc7e5ae43962ec2dda92d450d6b10c3d
156 Risk Score

Malware Insights

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

The PDF was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, directing users to multiple potentially compromised websites. 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 0.9975

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://completecollegestrategies.com/wp-content/plugins/super-forms/uploads/php/files/84907bf0319cd1afb51153607103bd61/rulerixuzok.pdf In PDF document text
    • http://nomaquito-travel.com/editor-images/58552891970.pdfIn PDF document text
    • https://www.andyselfstorage.co.uk/wp-content/plugins/super-forms/uploads/php/files/r35j236gif1hcot5jkuebnb3c5/temofazetofosesal.pdfIn PDF document text
    • https://dbjadow.pl/attachments/file/kabifuwimorofobimu.pdfIn PDF document text
    • https://cosplay-expo.it/ckfinder/userfiles/files/folazogofafotatewemevo.pdfIn PDF document text
    • http://www.masozilina.sk/ckfinder/userfiles/files/14967460760.pdfIn PDF document text
    • http://biosite.ru/images/news/file/widinefenixuguf.pdfIn PDF document text
    • http://yaeram.com/userData/board/file/garitugezufogimiveru.pdfIn PDF document text
    • https://www.die-umzugsfabrik.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606efb0ac9eda---nubeminunokuzukiwaka.pdfIn PDF document text
    • https://humanistbeauty.com/wp-content/plugins/super-forms/uploads/php/files/306nhvhhi9vkcvurqmlja4vll4/76159606469.pdfIn PDF document text
    • https://limpjet.com.br/wp-content/plugins/super-forms/uploads/php/files/fd441c63d79aaec7ddc4cbbc1abc8a28/durototonotumaxelopi.pdfIn PDF document text
    • http://www.marsagri.com/wp-content/plugins/formcraft/file-upload/server/content/files/160ec5211b10ca---45400839574.pdfIn PDF document text
    • https://superchills.com/userfiles/file/29693991237.pdfIn PDF document text
    • https://diversifiedhumansolutions.com/wp-content/plugins/super-forms/uploads/php/files/57bfe1c937423905d027613dff475f8a/99458708912.pdfIn PDF document text
    • http://inlygiaylynhua.com/upload/files/bufusaturodeka.pdfIn PDF document text
    • https://curvy.tw/upload/files/73811178352.pdfIn PDF document text
    • http://www.birapart.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b34a7137a84---84614128321.pdfIn PDF document text
    • https://dwitunggaljaya.com/sitefiles/file/duwakepavekepimuturavel.pdfIn PDF document text
    • http://mariancozma.com/_user/file/96069718869.pdfIn PDF document text
    • https://evboosters.com/wp-content/plugins/super-forms/uploads/php/files/c296c98b4c3b9f69b95c4e67c1baa6ec/pezeniwelukifibuwowugovem.pdfIn PDF document text
    • http://www.klpreschool.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606c95d504b18---fepowalob.pdfIn PDF document text
    • http://asesoriagarpe.com/wp-content/plugins/formcraft/file-upload/server/content/files/1609cd5b9af91b---gorupani.pdfIn PDF document text
    • https://storage-in-motion.com/wp-content/plugins/formcraft/file-upload/server/content/files/16098bf6b5455c---93556512954.pdfIn PDF document text
    • http://antwerp-rentals.com/wp-content/plugins/formcraft/file-upload/server/content/files/1609808249efd2---koxumekepis.pdfIn PDF document text
    • http://lnianemarzenie.pl/userfiles/file/4127691787.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/S30rS-6n6vg/uplcv?utm_term=percent+of+a+whole+number+word+problems+worksheetPDF 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_off0000d350.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD350 16900 bytes
SHA-256: b64c89844b245099ec5b75c04383f2484c2dcb350115450011ba7ba24084a8a8
font_01_sfnt_off0000ff22.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFF22 11212 bytes
SHA-256: 0c17033e6c80c0fb94c20dc1df8ec03e8fbdaaedde94b0bcf538cd6e339a7a0f
font_02_sfnt_off00011915.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11915 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1