Malicious PDF — malware analysis report

Static analysis result for SHA-256 2537f497ba97cffd…

MALICIOUS

PDF

101.5 KB Created: 2021-09-02 21:24:20 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-23
MD5: d06de2d96222f590f33fc3a2a3227f35 SHA-1: 5f8dec27860cdb801743eb7485c9743bd403b2be SHA-256: 2537f497ba97cffd84cd67e8eb54fa32561e79dca6bba126f063bf8a07812751
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file is identified as malicious by ClamAV and an ML classifier, with multiple heuristics indicating it's a link farm hosted on compromised CMS uploads. The embedded URLs, such as 'https://krisoc.ru/uplcv?utm_term=a+simplified+guide+to+structured+cobol+programming+pdf', likely lead to phishing pages or further malware. The PDF structure and the nature of the URLs suggest an attempt to lure users to malicious content, consistent with a phishing or malware distribution campaign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9961

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://krisoc.ru/uplcv?utm_term=a+simplified+guide+to+structured+cobol+programming+pdf PDF link annotation
    • https://www.gml.de/wp-content/plugins/formcraft/file-upload/server/content/files/1607de35fd85f1---3295662801.pdfIn PDF document text
    • http://slesnick.net/userfiles/files/risogakilipe.pdfIn PDF document text
    • https://paymentor.nl/uploads/file/xebalixabiduse.pdfIn PDF document text
    • https://aquariumfargo.com/wp-content/plugins/super-forms/uploads/php/files/6d1f2f21ac187c4a5ed51400704dc480/27818246699.pdfIn PDF document text
    • https://thewentworthco.com/wp-content/plugins/super-forms/uploads/php/files/pdoisj6idrgatpkdb4ctq31g6c/15451187751.pdfIn PDF document text
    • https://alate.org/admin/fckeditor/editorfile/63703656095.pdfIn PDF document text
    • https://iamtimeshare.com/userfiles/file/67354474308.pdfIn PDF document text
    • https://stellabakingcompany.com/wp-content/plugins/formcraft/file-upload/server/content/files/160fc269bdfdb3---68092046253.pdfIn PDF document text
    • https://www.frankcapassoandsons.com/wp-content/plugins/formcraft/file-upload/server/content/files/160ac2e92cf33a---16146889722.pdfIn PDF document text
    • https://www.hsbofmn.com/ckfinder/userfiles/files/nidoselej.pdfIn PDF document text
    • http://albino-pitti.com/pub_img/file/pofasisuxew.pdfIn PDF document text
    • http://carmakers.cz/userfiles/files/tafiwonekenugemolawe.pdfIn PDF document text
    • http://graviroz.hu/ckfinder/userfiles/files/58119017898.pdfIn PDF document text
    • http://tycoonmedical.com/userfiles/file/jenemuz.pdfIn PDF document text
    • http://www.nisbd.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607b002a00e0d---zisufudevowejokumejeb.pdfIn PDF document text
    • http://studioboscono.it/userfiles/files/kovubawizamowalusagu.pdfIn PDF document text
    • http://www.kinoimaging.nl/wp-content/plugins/formcraft/file-upload/server/content/files/160a7a7a46c91a---madoxumofewosesadakunona.pdfIn PDF document text
    • https://rmdschoolandcollege.com/wp-content/plugins/super-forms/uploads/php/files/sm216pmqvts571s9dorv5dojg1/fedikiri.pdfIn PDF document text
    • http://lotusburbank.com/uploads/files/54716948.pdfIn PDF document text
    • http://saveondealz.com/ckeditor/ckfinder/core/connector/php/uploads/files/53838096256.pdfIn PDF document text
    • http://bukharajohnscreek.com/sites/default/files/file/79877162720.pdfIn PDF document text
    • http://www.segurosfacility.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/160751ea991976---77184773846.pdfIn PDF document text
    • https://ladangmimpi.com/contents/files/2718184891.pdfIn PDF document text
    • http://vin-baietii.ro/ckfinder/userfiles/files/3376867884.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_off00012407.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12407 19388 bytes
SHA-256: 8986c9b3c6e729869ebe90f4adcbc8f4a42b14e6a472d4c79af98f6f86c24a03
font_01_sfnt_off00015607.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x15607 11184 bytes
SHA-256: 4f6115e1b735b75b68d57a1dfb5efd7e46702fef1f7aa7856ee65a9d65494299
font_02_sfnt_off00016fc0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x16FC0 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1