Malicious PDF — malware analysis report

Static analysis result for SHA-256 b837515c6711d7f2…

MALICIOUS

PDF

75.7 KB Created: 2021-06-25 12:25:27 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-08-25
MD5: 2b7076847919a42532af9841f140accb SHA-1: ca633e43d8ff3933b66a26915dfa33a7cc74fb55 SHA-256: b837515c6711d7f27336cb8957903585d8b3e173acffaacfe5012ca433ba238e
96 Risk Score

Malware Insights

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

The ML classifier strongly indicates maliciousness, supported by heuristics identifying the PDF as a link farm hosted on compromised CMS uploads. The document body is unreadable, but the presence of numerous URLs, many pointing to WordPress upload directories, suggests an attempt to redirect users to malicious content. The primary attack pattern involves leveraging these links, likely for phishing or malware delivery.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9993

Heuristics 5

  • 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://dfa-finanz.de/wp-content/plugins/formcraft/file-upload/server/content/files/160bc3f641f13d---856894301.pdf In PDF document text
    • https://kodeac.com/wp-content/plugins/super-forms/uploads/php/files/s9d4gr4sfo3u52eifgdc94r090/gosoxoresobelukabegu.pdfIn PDF document text
    • https://canadiancontractorservices.com/wp-content/plugins/super-forms/uploads/php/files/gt1ioq5ahd695eh8mcsh2i01q0/18272149202.pdfIn PDF document text
    • https://advancedcheckcashadvance.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606ff42546845---19137238722.pdfIn PDF document text
    • https://diversified-nj.com/wp-content/plugins/super-forms/uploads/php/files/8d9236142b1972190530546ae92ece65/lajefafav.pdfIn PDF document text
    • http://mattstergamer.com/wp-content/plugins/super-forms/uploads/php/files/btfhtm50mhtko5mgupisnnna7i/9206657468.pdfIn PDF document text
    • https://dermo.com/wp-content/plugins/formcraft/file-upload/server/content/files/160737463d9fa6---1911103375.pdfIn PDF document text
    • https://kindliving.org/wp-content/plugins/super-forms/uploads/php/files/tmp/60587230396.pdfIn PDF document text
    • http://grandchainfamilyfoundation.org/clients/85333/File/nimavitewojaputemurupo.pdfIn PDF document text
    • http://lichnyiybrand.ru/wp-content/plugins/formcraft/file-upload/server/content/files/16080dd3d40fed---palowokijufemubisam.pdfIn PDF document text
    • http://pulsrmedia.com/wp-content/plugins/formcraft/file-upload/server/content/files/160c19280692df---fopefajironope.pdfIn PDF document text
    • http://www.telsercom.com/wp-content/plugins/formcraft/file-upload/server/content/files/160728e6f8fed2---fitokuzepufuzaneso.pdfIn PDF document text
    • https://allianceflooring.net/wp-content/plugins/super-forms/uploads/php/files/162819723215a6f6a093297d4bc9c20a/7269050515.pdfIn PDF document text
    • http://tfh-filter.hu/_user/file/xezojexixevo.pdfIn PDF document text
    • https://www.verpoort-bouw.be/wp-content/plugins/formcraft/file-upload/server/content/files/160c238b59cac4---bogurubifog.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/ngfLrbzwjls/uplcv?utm_term=executive+protection+manual+pdfPDF link annotation
    • https://bxthirteen.wpengine.com/wp-content/plugins/super-forms/uploads/php/files/ee623e964b1f636f5cb8ff11fea56315/5194565131.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_off0000c54a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC54A 16764 bytes
SHA-256: 628e8d6b63f807291213892d9e5be5516ccf92148e67090b5573a859f515955a
font_01_sfnt_off0000f0f1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF0F1 10864 bytes
SHA-256: 50d204e4b5f6adfdcb8e58c8e22ad697b16b81d0055179d19c00909fb4f4f4a2
font_02_sfnt_off00010a08.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10A08 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1