Malicious PDF — malware analysis report

Static analysis result for SHA-256 139ec780e21bb803…

MALICIOUS

PDF

73.4 KB Created: 2021-06-24 23:24:56 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-09-14
MD5: d187478058c5ffb1df9d83efeda16253 SHA-1: 7de1823beb073a94631506cc6faf576cae217989 SHA-256: 139ec780e21bb8037d57f4bb37cde27680f42fdf913d92d32b2abd1818e5d514
156 Risk Score

Malware Insights

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

The PDF contains a large number of embedded URLs, many of which point to compromised WordPress sites hosting other PDF files. The ML classifier and ClamAV detection strongly indicate malicious intent, likely for phishing or distributing further malware. The document body is heavily obfuscated and appears to be a lure related to IELTS writing samples, but the primary malicious function is the link farm.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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://altaspin.com/calisma2/files/uploads/rolidefezowuwijusojiz.pdf In PDF document text
    • http://global-poseg.com/wp-content/plugins/formcraft/file-upload/server/content/files/160a80e1e1a430---dalupabunaxiwekokilij.pdfIn PDF document text
    • https://extremetour74.ru/wp-content/plugins/super-forms/uploads/php/files/8497e1de7a949068418e7c2eede75422/36281342734.pdfIn PDF document text
    • https://jiptv.nl/wp-content/plugins/super-forms/uploads/php/files/c1u561u9obr1uc44200tsb6s4r/34211270853.pdfIn PDF document text
    • https://anzmrrn.org/wp-content/plugins/formcraft/file-upload/server/content/files/16077d31ac417a---ranufewagatimilonuw.pdfIn PDF document text
    • https://thieumaunao.vn/workspace/develop/uploads/ck_upload/files/fepenagimosorusamov.pdfIn PDF document text
    • https://www.sadcmedia.com/wp-content/plugins/super-forms/uploads/php/files/bpaiel28dr4c3d54sbumpbcprl/64327632755.pdfIn PDF document text
    • https://www.caesarstravel.com/wp-content/plugins/formcraft/file-upload/server/content/files/160c7779320937---tegaguza.pdfIn PDF document text
    • http://asijskepotraviny.cz/files/file/34435551518.pdfIn PDF document text
    • http://makinsushi.com/uploads/files/zixizotuguzajukozisotale.pdfIn PDF document text
    • http://php-lounge.de/userfiles/file/37970764577.pdfIn PDF document text
    • http://urparitet.ru/admin/ckfinder/userfiles/files/loboruzokujegajaroj.pdfIn PDF document text
    • http://adamlegal.com/userfiles/file/85887792203.pdfIn PDF document text
    • https://stagerightstaging.com/wp-content/plugins/super-forms/uploads/php/files/39e52cdd31658df6146b5bd08d253bcb/2141553210.pdfIn PDF document text
    • http://ttlengenharia.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/160720e31b46c1---gafolimenefipaguk.pdfIn PDF document text
    • https://www.sir.co.uk/wp-content/plugins/formcraft/file-upload/server/content/files/160c422af83ccd---40387430112.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/fzgW7-mxBc0/uplcv?utm_term=ielts+writing+task+1+table+chart+sample+answersPDF 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e1dd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE1DD 5632 bytes
SHA-256: 491ad0f49ff228a3bc64711282ae89a0cb2c4a8016d7d61684f08660f18e82a1
font_01_sfnt_off0000f4f2.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF4F2 10416 bytes
SHA-256: 40b48f554bf82a783c3a7ac830e6912430cac064bc2939f9e7b536e380be424c