Malicious PDF — malware analysis report

Static analysis result for SHA-256 d61b4c451918c3d8…

MALICIOUS

PDF

80.8 KB Created: 2021-09-05 08:51:53 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-05
MD5: 3a8f9284e2f159e7104a9c83d63e1db7 SHA-1: 942cb448049594978f0ad3cd5bcbb1b8b5739744 SHA-256: d61b4c451918c3d86f1fe548f1cfe6b096a16aa8f6340684fd1a8518190553c6
156 Risk Score

Malware Insights

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

The PDF file was identified as malicious by ML classifiers and ClamAV, specifically flagged as a phishing trojan. Heuristics indicate it functions as a link farm, with many URLs pointing to compromised CMS upload directories. The document body is heavily obfuscated and contains no readable content, suggesting its primary purpose is to host these malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9846

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://gerastar.com/userfiles/file/7789328888.pdf In PDF document text
    • http://novussiteyonetimi.com/uploads/file/43391173630.pdfIn PDF document text
    • http://myphammonly.com/luutru/files/vepafuzeju.pdfIn PDF document text
    • http://zkojicin.cz/userfiles/file/47715143045.pdfIn PDF document text
    • https://www.shopveriamici.com/wp-content/plugins/super-forms/uploads/php/files/i6vi5ancrkp5sd77bqd1da8bbn/gawulomixasiz.pdfIn PDF document text
    • http://catgarner.com/clients/873270/File/jolis.pdfIn PDF document text
    • http://covina.crazyrockinsushi.com/uploads/files/redulusetewepemekepu.pdfIn PDF document text
    • https://www.oasipizza.it/wp-content/plugins/formcraft/file-upload/server/content/files/16089cb370782c---14661738985.pdfIn PDF document text
    • http://bagandpack.ru/wp-content/plugins/super-forms/uploads/php/files/c7a2a9aa46182f07d730712adfc18474/kuwegiliwelefikerenilir.pdfIn PDF document text
    • https://maloneslandscape.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608639142cade---zuxoxilunukon.pdfIn PDF document text
    • http://www.1000ena.com/wp-content/plugins/formcraft/file-upload/server/content/files/160de211bb496e---xoxumutexoduxuvopajibuv.pdfIn PDF document text
    • http://archidaldegan.eu/userfiles/files/21316979673.pdfIn PDF document text
    • http://asesorgubernamental.com/images/file/53679153099.pdfIn PDF document text
    • https://www.xtremefitness.com.au/application/third_party/ckfinder/userfiles/files/nokore.pdfIn PDF document text
    • https://webtraffic.ch/wp-content/plugins/super-forms/uploads/php/files/9lpbbkainqfcsuob39skp9j0se/nibus.pdfIn PDF document text
    • https://www.numberoneporthill.co.uk/wp-content/plugins/formcraft/file-upload/server/content/files/160a6b390023de---88119125164.pdfIn PDF document text
    • https://www.sahabatkeluargahomecare.com/wp-content/plugins/formcraft/file-upload/server/content/files/16079ea93742fd---xusefonuponaxikubozoxo.pdfIn PDF document text
    • http://www.dean-cpa.com/files/adminpic/file/wowomiwujolodawufaranoser.pdfIn PDF document text
    • http://richmore.kr/uploadfile/fckeditor/file/wewidakov.pdfIn PDF document text
    • https://mecaniquekd.ca/upload/file/sakoluroleda.pdfIn PDF document text
    • http://bagpack.com.np/wp-content/plugins/formcraft/file-upload/server/content/files/1608d69229e7c9---67291810599.pdfIn PDF document text
    • http://www.kliningstroy.ru/wp-content/plugins/formcraft/file-upload/server/content/files/160fffacf6b7ec---bipivedugedobikelem.pdfIn PDF document text
    • https://viajespereira.com/wp-content/plugins/formcraft/file-upload/server/content/files/160f5a3a04bf74---44072889564.pdfIn PDF document text
    • https://activepymes.com/pub/file/fomazog.pdfIn PDF document text
    • http://fortlauderdalelimorental.net/wp-content/plugins/formcraft/file-upload/server/content/files/1607766ec28afc---26597534629.pdfIn PDF document text
    • http://uat.ideadunes.com/projects/ideadunes-portfolio-site/wp-content/plugins/formcraft/file-upload/server/content/files/1607df65d6ab62---rafejegudabebe.pdfIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/BkSY9tpko7c/uplcv?utm_term=vacuna+contra+tetanos+pdfPDF 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d772.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD772 18316 bytes
SHA-256: 0a81ab4b3ee5ef9cd7ea1a67251b39ad4572452a39caa88a3ac0fc9805dc4cf0
font_01_sfnt_off00010557.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10557 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00011d6e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11D6E 10544 bytes
SHA-256: 9b01d56c04e933b09f3fb0c7641781a5e26b7cce28aa4456c4d8551f3392e938