Malicious PDF — malware analysis report

Static analysis result for SHA-256 5a66728557e43e5c…

MALICIOUS

PDF

88.5 KB Created: 2021-09-11 13:41:45 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 8b20de31f67b8115bee071cb8aa320d0 SHA-1: 312bc16aa1f46dffafb1455841072d1d4bf715a5 SHA-256: 5a66728557e43e5c80f4df1d3fc5761061a9082496bf139004a7517a6ee74491
164 Risk Score

Malware Insights

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

This PDF file was flagged by multiple heuristics, including a critical ClamAV detection and an ML classifier, indicating malicious intent. It contains an embedded JavaScript stream and numerous external URIs, many pointing to compromised WordPress sites or disposable hosting, suggesting it functions as a link farm to distribute further malicious content. The presence of JavaScript indicates an attempt to execute code, likely to download and run a second-stage payload.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

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://synerhu.ru/uplcv?utm_term=casual+games+android PDF link annotation
    • https://ms2oke.com/contents/files/soveliwowisi.pdfIn PDF document text
    • https://izharfoster.com/wp-content/plugins/formcraft/file-upload/server/content/files/1612f7f620faad---putoxedeso.pdfIn PDF document text
    • https://jnnjhansi.com/userfiles/file/zewop.pdfIn PDF document text
    • https://emergent-partners.com/wp-content/plugins/formcraft/file-upload/server/content/files/16136cbfe227ac---fifegibekodojuri.pdfIn PDF document text
    • https://sledovani2.gpshlidac.cz/www/userfiles/files/xumeju.pdfIn PDF document text
    • http://kerrya.com/ckfinder/userfiles/files/70317557731.pdfIn PDF document text
    • http://www.hro.ait.ac.th/js/ckfinder/userfiles/files/xosasarixubadureru.pdfIn PDF document text
    • http://szilasfood.hu/pic_upload/files/42708870647.pdfIn PDF document text
    • http://konditsionery-zheleznodorozhnyi.ru/upload_picture/file/pikavosegabu.pdfIn PDF document text
    • http://nfc-lampang.com/user_img/files/fadurakabev.pdfIn PDF document text
    • http://emrc.ie/upload/imagecontent/file/piturezejikunoj.pdfIn PDF document text
    • http://restauraceeverest.cz/userfiles/file/6462733803.pdfIn PDF document text
    • https://www.energetisch-therapeut-estie.nl/wp-content/plugins/formcraft/file-upload/server/content/files/16137f20917b01---73645621990.pdfIn PDF document text
    • http://hopkim.vn/upload/files/dovaputokavi.pdfIn PDF document text
    • http://avs-market.ru/admin/ckfinder/userfiles/files/kamolan.pdfIn PDF document text
    • http://www.celso.org/download/xiwuvawodimibelijilobapam.pdfIn PDF document text
    • http://www.maarsehoveniers.nl/wp-content/plugins/formcraft/file-upload/server/content/files/1613ac9fabaf2d---59183243712.pdfIn PDF document text
    • http://radyoislam.com/resimler/files/xolatoxopakofovijovap.pdfIn PDF document text
    • http://donateagift.eu/userfiles/file/80452496488.pdfIn PDF document text
    • http://chalappuram.com/userfiles/file/47345658708.pdfIn PDF document text
    • https://penmypoem.com/new/admin/uploadfiles/file/45353922670.pdfIn PDF document text
    • http://24hnbc.com/assets/ckfinder/core/connector/php/uploads/files/lijiveka.pdfIn PDF document text
    • http://teresachild.com/upload/files/24429952530.pdfIn PDF document text
    • http://lnaixi.com/userfiles/file/20210910215307_1640494325.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_off0000f880.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF880 16904 bytes
SHA-256: aee1ea6d7d1ecad6080df56643c7ee22984db3012fd9477a0f02acba727f0910
font_01_sfnt_off00012463.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12463 10624 bytes
SHA-256: ad2c71dc14b7fa051c7ac7cd6516c6461ff3ce0c0dde204adf8016551a177f7d
font_02_sfnt_off00013c67.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13C67 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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