Malicious PDF — malware analysis report

Static analysis result for SHA-256 f33ebd3def56bf56…

MALICIOUS

PDF

79.8 KB Created: 2021-09-20 19:32:08 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-14
MD5: f01bd4da9ea6e376afbfbb7ecfb3aafe SHA-1: d6006f79201e81c37062abe328b3d39b3b89a349 SHA-256: f33ebd3def56bf567b18ad2747bd29e113291a09916c16bc996690bdfc4e2a17
156 Risk Score

Malware Insights

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

The PDF contains numerous embedded URLs pointing to various domains, many of which are identified as link farms on disposable or potentially compromised hosting. The ML classifier and ClamAV detection strongly indicate malicious intent, likely phishing or malware delivery. The document body is heavily obfuscated and appears to be non-readable content generated by wkhtmltopdf, providing no direct user-facing lure.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9977

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://synerhu.ru/uplcv?utm_term=postcode+upper+kedron PDF link annotation
    • http://maturitni-ples.eu/UserFiles/File/86183874781.pdfIn PDF document text
    • https://soi.icami.mx/ckfinder/userfiles/files/89413016103.pdfIn PDF document text
    • http://sieckultury.pl/wp-content/plugins/super-forms/uploads/php/files/ec418988961a331a7263cd3491136390/82863124462.pdfIn PDF document text
    • http://kalmi.ru/upfiles/files/tofufenevozudelexofozeza.pdfIn PDF document text
    • http://regcureguide.com/files/files/girafax.pdfIn PDF document text
    • https://alperbehang.nl/userfiles/file/letixupudolaxaruwaribi.pdfIn PDF document text
    • https://pikhospital.com/ck_uploads/uploads/files/81614753586.pdfIn PDF document text
    • https://formapolis.it/wp-content/plugins/super-forms/uploads/php/files/073a6185d73774a6430c5bab62d64a5e/wibariwajofuwu.pdfIn PDF document text
    • https://vildmarksjagt.dk/userfiles/file/kaxizogixibiz.pdfIn PDF document text
    • http://yjbiotech.cn/upload/files/misumojox.pdfIn PDF document text
    • http://scoutpate.com/userfiles/file/polepekeranidupof.pdfIn PDF document text
    • http://myrbacken.se/login/ckfinder/userfiles/files/72893637478.pdfIn PDF document text
    • http://www.psstrecno.sk/wp-content/plugins/formcraft/file-upload/server/content/files/16145335fef970---66442218623.pdfIn PDF document text
    • http://nsdadventist.org/FCKData/file/vipipej.pdfIn PDF document text
    • http://sanfrancescovet.com/userfiles/files/34624785543.pdfIn PDF document text
    • https://tkpmission.org/wp-content/plugins/formcraft/file-upload/server/content/files/16135322f9bd73---favezuduw.pdfIn PDF document text
    • http://le383.com/uploads/files/zojosigariwubon.pdfIn PDF document text
    • http://adria-ex.com/images/blog/file/pigetukudomonejuz.pdfIn PDF document text
    • http://kprmk.pl/userfiles/file/wetapuzesebiwipezope.pdfIn PDF document text
    • https://bodymart.in/ckfinder/userfiles/files/4338961320.pdfIn PDF document text
    • http://strahyi.ru/images/file/56676413267.pdfIn PDF document text
    • http://atenngo.com/admin/sites/site/documents/71012441696.pdfIn PDF document text
    • https://mcq.bmtinhoc.vn/InteriorWeb/images/images_news/files/99119566864.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_off0000d10a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD10A 18408 bytes
SHA-256: 0ac161c4c3a3423e2d64ce5dda8f7599b7d0052a818fa7e5ca32b3c744adb785
font_01_sfnt_off000101b4.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x101B4 10400 bytes
SHA-256: 2d78b1c2f6d50b6378ca67439ac6d500d6c4710a8ce138e533244edecd61ffe0
font_02_sfnt_off00011975.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11975 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1