Malicious PDF — malware analysis report

Static analysis result for SHA-256 b4b8cb4f4893a68a…

MALICIOUS

PDF

84.3 KB Created: 2021-09-12 01:05:10 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-11
MD5: 99d4e22bba08d412fd6bd425bba3279a SHA-1: 9ada51caa427dd92b3dadfe26e89b9908f5f7643 SHA-256: b4b8cb4f4893a68a845e56e1b8531525c0ca063b749249c5cf6df40a90556868
156 Risk Score

Malware Insights

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

The PDF file was flagged by multiple heuristics and a machine learning classifier as malicious, with ClamAV detecting it as a phishing trojan. It contains numerous links pointing to potentially compromised websites and disposable hosting, suggesting a link farm designed to redirect users to malicious content. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, indicating it's not intended for human readability but rather as a container for malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9877

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 http://fiumaradelsossio.it/userfiles/files/93520432647.pdf In PDF document text
    • http://greathorserider.com/ckfinder/userfiles/files/nomamijotusivatutejole.pdfIn PDF document text
    • https://gulfsupremesa.com/ckfinder/userfiles/files/gogabok.pdfIn PDF document text
    • https://vienhung.com/webroot/img/files/velirekakoja.pdfIn PDF document text
    • https://simondaulte.com/ckfinder/userfiles/files/faxokunadokaxapo.pdfIn PDF document text
    • http://toanthinh.vn/webroot/img/files/21174840818.pdfIn PDF document text
    • https://satybharat.com/ci/userfiles/files/64199929059.pdfIn PDF document text
    • http://stark-tools.ru/images/uploaded/56502638986.pdfIn PDF document text
    • http://thietbianninh188.com/uploads/files/lenaveduwumesuna.pdfIn PDF document text
    • https://bettenbaehren.de/wp-content/plugins/formcraft/file-upload/server/content/files/161372ebe7a40d---44370716700.pdfIn PDF document text
    • https://fminterativa.net/cms/plugins/ckfinder/userfiles/files/laduzoxinufoparor.pdfIn PDF document text
    • http://tsnpharma.com/upload/files/kisupiwixodolix.pdfIn PDF document text
    • http://raduzhniy.com/wp-content/plugins/formcraft/file-upload/server/content/files/161392a3830703---66248286131.pdfIn PDF document text
    • http://ydtmuhendislik.com/ckfinder/userfiles/files/lidurudagapotipobevufod.pdfIn PDF document text
    • http://unibeauty.com.br/ckfinder/userfiles/files/66945151945.pdfIn PDF document text
    • https://funke.be/data/file/30374770943.pdfIn PDF document text
    • https://winpoasia.com/ckfinder/userfiles/files/45665877529.pdfIn PDF document text
    • https://digireg.dk/upload/nixekovogemowixu.pdfIn PDF document text
    • http://neodermclinic.com/file_media/file_image/file/nakufape.pdfIn PDF document text
    • http://konikanarrowfab.com/ckfinder/userfiles/files/35953718721.pdfIn PDF document text
    • https://tbsva.org/Upload/files/20210906221311.pdfIn PDF document text
    • http://veiligheidssloten.nl/ckfinder/userfiles/files/duzifukoxatafipimofuf.pdfIn PDF document text
    • https://www.fifatravels.com/wp-content/plugins/formcraft/file-upload/server/content/files/1612f6a01eeb17---76747989019.pdfIn PDF document text
    • http://design-klasse.de/ckfinder/userfiles/files/40527094577.pdfIn PDF document text
    • http://kleinschadenexpert.com/userfiles/file/4362423954.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/FevRqgeaUVY/uplcv?utm_term=principles+of+instrumental+analysis+5th+editionPDF 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 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000b94e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB94E 20664 bytes
SHA-256: 0f1866078a216bb32be5761bf3f29043a3e6415af776ef69454ed2ba667b4afa
font_01_sfnt_off0000ef2d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEF2D 11232 bytes
SHA-256: d9cc0c80a93eee0f65dac95af94944a52c9fa66726a25f021bb152a246f6aa24
font_02_sfnt_off00010959.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10959 16484 bytes
SHA-256: 516071a29714a63f65c50a5251385f68dc3d2d26f078a38625244bcae2f04bf8
font_03_sfnt_off00012049.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12049 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_04_sfnt_off00013856.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13856 2232 bytes
SHA-256: b7f8508df8036e76473c710e3f35b391a4be9ba3f2caf03c46ca2c11c2350c48