Malicious PDF — malware analysis report

Static analysis result for SHA-256 57a433fc38e34a98…

MALICIOUS

PDF

93.0 KB Created: 2021-09-03 05:51:46 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-24
MD5: 85400f43d52c83950a650b5ba80216b7 SHA-1: ea760998976fc8eb0f1e2cc1adc4233aaf6b9910 SHA-256: 57a433fc38e34a985d5044ea513fb62c9f3db79a060ca69c1b277a3869a6b317
176 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF file was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. Heuristics reveal numerous external URIs, including links to compromised WordPress uploads and disposable hosting, suggesting a phishing or malware distribution scheme. The document body, though heavily obfuscated, contains metadata indicating it was generated by wkhtmltopdf, a tool often used to create malicious PDFs. No scripts were extracted, but the numerous embedded URLs are the primary indicators of malicious activity.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9956

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
  • Clickable URI points to raw IP address medium PDF_URI_IP_LITERAL
    PDF contains a clickable HTTP(S) action whose host is a literal IPv4 address. Legitimate documents normally link to named domains; raw-IP destinations are common in disposable phishing and malware-delivery infrastructure.
  • 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://krisoc.ru/uplcv?utm_term=whodunnit+worksheet+answer+key PDF link annotation
    • http://inventory-acepipe.com/images/uploads/files/22510012761.pdfIn PDF document text
    • https://www.kiteschule-kiel.de/wp-content/plugins/formcraft/file-upload/server/content/files/16083faf05a571---52845441763.pdfIn PDF document text
    • http://tokyosushilohaus.com/uploads/files/67955669449.pdfIn PDF document text
    • http://idcla.net/upload/files/47438711298.pdfIn PDF document text
    • https://cambodiadriverservice.com/userfiles/file/38740892374.pdfIn PDF document text
    • http://chothuexehochiminh.com/userfiles/file/39858081552.pdfIn PDF document text
    • http://www.appsolutely.sg/wp-content/plugins/formcraft/file-upload/server/content/files/16082635e1e88a---27874197637.pdfIn PDF document text
    • http://servmed.net/userfiles/file/70784307509.pdfIn PDF document text
    • http://ulleungroadtour.com/FileData/ckfinder/files/20210823_A24B8DAF46476815.pdfIn PDF document text
    • https://relleno-acidohialuronico.com/wp-content/plugins/super-forms/uploads/php/files/b320d388f0992361f8b48d5d07a9c618/lefovixonedepem.pdfIn PDF document text
    • https://encoregallery.us/wp-content/plugins/super-forms/uploads/php/files/e9a87cd2bb51a769354aca8d6e36fe35/2944293494.pdfIn PDF document text
    • http://www.hj-bouwt.be/wp-content/plugins/formcraft/file-upload/server/content/files/1612e703d2e652---bezuwewipefuve.pdfIn PDF document text
    • http://www.champcaregivers.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b61b8b49a9b---54122409216.pdfIn PDF document text
    • http://ahjygjg.com/upload_fck/file/2021-8-29/20210829212422217508.pdfIn PDF document text
    • https://eliteplacementagency.com/uploads/files/93712070402.pdfIn PDF document text
    • http://mmbc.cz/_data/user_files/file/40141839972.pdfIn PDF document text
    • http://sjhrz.com/images/upload/File/73145665766.pdfIn PDF document text
    • http://alituncer.com/userfiles/file/mepeluv.pdfIn PDF document text
    • https://www.coconutlodge.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607768418b9d0---54407696603.pdfIn PDF document text
    • https://www.eziblank.com/wp-content/plugins/super-forms/uploads/php/files/5m924rrmrge8i29k3id824h2p2/55768677539.pdfIn PDF document text
    • http://157.230.241.115/image/upload/File/15498508800.pdfPDF link annotation
    • http://raykingcarroll66.com/clients/2/29/292092747e06e0ab09130fa737b110c0/File/91364926960.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_off0000ff84.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFF84 20052 bytes
SHA-256: f78ff77e2a6fd9944d109ee4412b2dbf3dbc83a69338cecf1def8c1aba8a736f
font_01_sfnt_off00013471.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13471 10684 bytes
SHA-256: 062e9d8c86dcb49bdd6d8aa0ba30b9b426eeae0e4209aaf6bd001c1e2a4a251f
font_02_sfnt_off00014d02.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x14D02 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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