Malicious PDF — malware analysis report

Static analysis result for SHA-256 ef256a9f3d9d0b40…

MALICIOUS

PDF

76.0 KB Created: 2021-06-05 04:04:07 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: f57efab5ebc81790f5161beca1b2bc81 SHA-1: 559f81b04a8cfa413b84bfe1c6521987419c3647 SHA-256: ef256a9f3d9d0b40b060c2a9535e5c369f82304587ef36849bdf8056d6c7cc68
96 Risk Score

Malware Insights

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

The PDF file contains numerous embedded links, many pointing to compromised WordPress sites and disposable hosting, suggesting a link farm or SEO poisoning tactic. The document body, though heavily obfuscated, contains keywords related to 'medical ethics pdf download', indicating a lure to trick users into visiting these malicious sites. The ML classifier strongly flagged this PDF as malicious, supporting the assessment of a malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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://krisoc.ru/uplcv?utm_term=medical+ethics+pdf+download
    • http://hillsdalehorseboarding.com/ckfinder/userfiles/files/vimigubivigibu.pdf
    • http://www.qookspot.kitchen/wp-content/plugins/formcraft/file-upload/server/content/files/160b30a7fca395---98564193193.pdf
    • http://www.marsagri.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608828f25797d---xudukizivosowabadozefaxuz.pdf
    • https://2greenchicks.com/wp-content/plugins/super-forms/uploads/php/files/5461b7516aeb3ab0197df05a9a31fa69/jibozujepogateza.pdf
    • http://beiwendq.com/userfiles/file/dawefolixoxeleroxe.pdf
    • http://mouaumfb.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607622ba6e5fa---fazudikobufimebebumevej.pdf
    • https://calldidocta.com/wp-content/plugins/super-forms/uploads/php/files/972b2524bc66a4eb7f0592ab4bb47530/21668964824.pdf
    • https://fortlauderdale-carservice.com/wp-content/plugins/formcraft/file-upload/server/content/files/160731630bbca1---10905938818.pdf
    • http://richmore.kr/uploadfile/fckeditor/file/7505757949.pdf
    • https://ajitcoatings.com/uploads/xusawusozuguliwowi.pdf
    • http://xn----8sbnbd9chja.xn--p1ai/userfiles/file/17252814129.pdf
    • https://www.sussexweddingservices.co.uk/wp-content/plugins/formcraft/file-upload/server/content/files/1606e4e97e5452---50396631309.pdf
    • http://rufullthrottle.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607427b7e2873---jedikaz.pdf
    • https://123kozijnofferte.nl/wp-content/plugins/super-forms/uploads/php/files/tnvosunhiao917edhbjd9anhr1/buvosezagebuj.pdf
    • http://avonsteel.com/UserFiles/file/sulowitigemefedu.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000ed61.bin
38c383f109cfd29ea691bbdecc527a4652e6846ea80f0001e7827d380c75f209		 pdf-font-stream PDF embedded font (sfnt) at offset 0xED61 5244 bytes
font_01_sfnt_off0000ff57.bin
be1ec741ada8ad8fed70ac3aaf3953ff9799644fb9b4735d20bc1568c4068d13		 pdf-font-stream PDF embedded font (sfnt) at offset 0xFF57 10396 bytes

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