Malicious PDF — malware analysis report

Static analysis result for SHA-256 5311b7c94c4b0e00…

MALICIOUS

PDF

119.7 KB Created: 2021-05-17 22:23:10 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: e55068cc2af52788a61235a4f462c2b3 SHA-1: 95b06c8b8fb03175a2b076a540ffb83b7d703f4e SHA-256: 5311b7c94c4b0e0067989b663d3e86783402e48c9415f7b6969d91c72db00938
164 Risk Score

Malware Insights

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

The PDF contains numerous links to compromised WordPress sites, many of which are disguised as academic resources or download prompts. The ML classifier and ClamAV detection strongly indicate malicious intent, likely to serve a phishing page or download a secondary payload. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create malicious PDFs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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
  • 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.
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • 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=khan+academy+geometric+transformations+unit+test+answers
    • http://raunlarose.us/wp-content/plugins/formcraft/file-upload/server/content/files/160858ea0c1752---31336449985.pdf
    • https://otdelkamos.ru/wp-content/plugins/super-forms/uploads/php/files/e02009635d43a296fd46761aeade3669/86504799629.pdf
    • https://macleanpinesdrivingschool.com.au/wp-content/plugins/super-forms/uploads/php/files/6670bcf1efe9cf3ccc35e9ef2917acbb/55910850836.pdf
    • https://www.budgetskemaet.dk/wp-content/plugins/formcraft/file-upload/server/content/files/16076e655a8011---jopomodimetazexu.pdf
    • http://allprintusa.com/admin/images/file/40469770279.pdf
    • http://www.onekaddy.com/wp-content/plugins/formcraft/file-upload/server/content/files/16084da248c505---31031743918.pdf
    • https://alcc.vn/wp-content/plugins/super-forms/uploads/php/files/n609tglqpqf6ckejfjqmh23511/76617068752.pdf
    • https://reinigungsfee007.de/wp-content/plugins/super-forms/uploads/php/files/lr17kec7jb37k0gc56psg0mp1i/mozabirowewimufanolusu.pdf
    • https://sirikulsteel.com/wp-content/plugins/formcraft/file-upload/server/content/files/16076381898662---nofizowosemizumita.pdf
    • https://jfefood.com/wp-content/plugins/super-forms/uploads/php/files/46dcc5da47bfbbbf167566c8824aa502/89034702327.pdf
    • http://asiadomainstore.com/userfiles/file/lupemufumoraxarobopo.pdf
    • http://a-range.ru/wp-content/plugins/formcraft/file-upload/server/content/files/16070d8e661015---jamozamal.pdf
    • http://www.fotografoeventimilano.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606f6ad9a92ca---muluwesibeteluserutubisu.pdf
    • https://autoschiller.de/wp-content/plugins/formcraft/file-upload/server/content/files/160909cfa767e0---fuzexevakupux.pdf
    • http://snookerfootball.eu/wp-content/plugins/formcraft/file-upload/server/content/files/1607ea4262bf46---87206677730.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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0001878e.bin
32e3ef710cd7109c0b36dc03950a88042ae812a545f31cab9e51e11f8dfd560e
pdf-font-stream PDF embedded font (sfnt) at offset 0x1878E 2900 bytes
font_01_sfnt_off000191dc.bin
5b0bb2f07de516d94a44edf561d95a1646e028f7fd0448c70cafd57cb3e2fafc
pdf-font-stream PDF embedded font (sfnt) at offset 0x191DC 5564 bytes
font_02_sfnt_off0001a4bd.bin
08c8c26ee92d0c0645431ecb34fcdebf5e398f8b0f36910ad1bff5121cddda4a
pdf-font-stream PDF embedded font (sfnt) at offset 0x1A4BD 13148 bytes