Malicious PDF — malware analysis report

Static analysis result for SHA-256 de35f87586a78b54…

MALICIOUS

PDF

87.4 KB Created: 2021-09-07 10:50:47 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: 1ecff521c27829fd761f195f039777da SHA-1: e5cc676c840550b9d4d1c66f567377dd4fc75b37 SHA-256: de35f87586a78b54433786d160e7119898b9e6b29ee95f0a3d68332ca2daa228
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF contains numerous embedded URLs, many of which point to external sites, including one hosted on a compromised WordPress upload directory. The ML classifier and ClamAV detection strongly indicate malicious intent, likely to lure users to malicious or compromised sites. The document body is heavily obfuscated and appears to be non-readable content generated by wkhtmltopdf, suggesting it's not intended for direct user interaction but rather as a container for malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9976

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://promobryansk.ru/userfiles/files/porixobaxiwoj.pdf In PDF document text
    • https://almavilag.hu/files/files/ximabober.pdfIn PDF document text
    • http://primebrokeragetx.com/ckfinder/userfiles/files/62178103346.pdfIn PDF document text
    • https://fminterativa.net/cms/plugins/ckfinder/userfiles/files/24857992402.pdfIn PDF document text
    • http://eros-arena.de/eros/userfiles/file/kejavilinerinuxasizikuzi.pdfIn PDF document text
    • http://bitite.lv/media/txt/122/file/74068103914.pdfIn PDF document text
    • https://apoiotelecom.com/imagens/img_fckeditor/file/80364196404.pdfIn PDF document text
    • http://siblom.ru/files/upload/file/dazonafikikaf.pdfIn PDF document text
    • https://www.azulejositurry.com/wp-content/plugins/super-forms/uploads/php/files/cadslk5bp5kku6t39510ripet6/39482390141.pdfIn PDF document text
    • http://mega-treid.com/userfiles/files/paxivudeged.pdfIn PDF document text
    • http://iccarrentals.com/files/file/sujopopozawerewimuk.pdfIn PDF document text
    • https://glass-haus.ru/wp-content/plugins/super-forms/uploads/php/files/7f307a8b5796c93566a0802f1e142bbd/28790005057.pdfIn PDF document text
    • https://cmetrix.net/ckfinder/userfiles/files/38153550358.pdfIn PDF document text
    • https://www.la-providence-ehpad.fr/ckfinder/userfiles/files/38898205350.pdfIn PDF document text
    • http://www.1000ena.com/wp-content/plugins/formcraft/file-upload/server/content/files/1612cad7fd1a3f---puresimefitasimi.pdfIn PDF document text
    • https://anakmeong.com/contents//files/wadigewofodezutipas.pdfIn PDF document text
    • https://mikepromedia.com/wp-content/plugins/super-forms/uploads/php/files/glf528pd1ucdt2kgih6deetps3/xemejabaxazejixogadido.pdfIn PDF document text
    • http://tsrmvolontari.it/userfiles/files/lulevomujevoladasojorudu.pdfIn PDF document text
    • https://fotoprint.lv/downloads/file/74339271727.pdfIn PDF document text
    • http://cetinelektrik.com.tr/wp-content/plugins/formcraft/file-upload/server/content/files/1608bf6fb77c81---27110897997.pdfIn PDF document text
    • https://herfection.tw/upload/ckfinder_temp/files/20210701024903.pdfIn PDF document text
    • http://gamboeng.com/assets/ckfinder/userfiles/files/nupefanagogusofurobe.pdfIn PDF document text
    • http://phrabat.net/UserFiles/File/19668117544.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/1KS0DP0cxss/uplcv?utm_term=mahendra+guru+vocabulary+pdf+downloadPDF 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_off0000e8ab.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE8AB 11040 bytes
SHA-256: 3229d7556d5fef0bd89b9acb7ba2969fc1c59e579283284dda8d5f2c2d0fe343
font_01_sfnt_off000101dd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x101DD 20412 bytes
SHA-256: 5f281cb1af21348586db8633f6112c044712fdd63f22a7ce09d1b86095e62c09
font_02_sfnt_off00013770.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13770 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1