Malicious PDF — malware analysis report

Static analysis result for SHA-256 857d94c3329bcbfe…

MALICIOUS

PDF

83.1 KB Created: 2021-09-08 03:49:03 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-05
MD5: f23db5f1a45274fcda159ae345edd0cb SHA-1: 5b9249fdb22bb600e2c472feb61ca356b33d68ac SHA-256: 857d94c3329bcbfe9363fda114705bf8e23c6026b7c2825ff33faafafb0ed037
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file was detected as malicious by ClamAV, indicating a phishing or trojan threat. It functions as a link farm, containing numerous URLs pointing to PDF files hosted on various domains, some of which are associated with compromised CMS uploads. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for direct user reading but rather as a container for these links. No scripts were extracted, but the nature of the links suggests a potential for further malicious content delivery or redirection.

Machine Learning

  • Nyx PDF Classifier clean score 0.2133

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
  • PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED
    The cross-check parser (pdfminer.six) failed on this file: PDF differential parser failed: PDFSyntaxError. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.
  • 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 http://tz5168.com/uploadfile/image/2021/07/23/file/20210723_144542_135.pdf In PDF document text
    • http://arqing.es/ckfinder/userfiles/files/27238941175.pdfIn PDF document text
    • http://asustainable.com/global/file/51141320581.pdfIn PDF document text
    • http://www.northeastmarquees.com/wp-content/plugins/super-forms/uploads/php/files/0fa462b153b3a47c7d7d4eeaa704494e/45144147825.pdfIn PDF document text
    • http://videoacceso.com/wp-content/plugins/formcraft/file-upload/server/content/files/160a7540bba8f6---fatoworewizadazimeta.pdfIn PDF document text
    • https://htfcompact.com/wp-content/plugins/super-forms/uploads/php/files/72cf5ca0a5ea83ad7faa2b9b6d95ce2c/32060052784.pdfIn PDF document text
    • http://hai-bi.com/uploads/files/202108160432513085.pdfIn PDF document text
    • https://nicemexico.net/wp-content/plugins/formcraft/file-upload/server/content/files/160897963db226---bivufevekedafewavefivesal.pdfIn PDF document text
    • https://activepymes.com/pub/file/xevarebeneg.pdfIn PDF document text
    • http://www.sarajevo-inn-grunewald.com/wp-content/plugins/formcraft/file-upload/server/content/files/160cb8496432bd---57682414313.pdfIn PDF document text
    • http://industrialdevices.in/uploads/42110205010.pdfIn PDF document text
    • http://www.julitolaschools.com/wp-content/plugins/formcraft/file-upload/server/content/files/160ba20c96b990---nekajuxu.pdfIn PDF document text
    • https://producedepot.us/userfiles/files/femujotatinotaka.pdfIn PDF document text
    • https://xn--z4qq44i.tw/upload/actfiles/73561516208.pdfIn PDF document text
    • http://onellenorzes.com/uploads/files/jodikura.pdfIn PDF document text
    • http://haozuowenwang.com/imagefiles/file/96950121564.pdfIn PDF document text
    • https://orkhaconstruction.com/wp-content/plugins/super-forms/uploads/php/files/3gcodicp3osb61s9refbfkpnj6/43496555198.pdfIn PDF document text
    • https://pk-kuepfer.ch/ckfinder/userfiles/files/vatesazal.pdfIn PDF document text
    • https://hobbes-group.com/upload/files/gipopavawakux.pdfIn PDF document text
    • http://austria-ex.com/images/blog//file/dokolilidefokudavak.pdfIn PDF document text
    • https://combrooncom.com/contents//files/3023413317.pdfIn PDF document text
    • http://for-rent-aalst.com/wp-content/plugins/formcraft/file-upload/server/content/files/160ad09e98ad8b---luxopixefinuxibuluvowejif.pdfIn PDF document text
    • http://apogeeconsultancy.com/upload/files/78101197800.pdfIn PDF document text
    • http://www.rec39.ru/wp-content/plugins/super-forms/uploads/php/files/a5bdafe13622defadeeabd54a62f1e85/jupufajogebizopar.pdfIn PDF document text
    • http://alnadaoil.com/userfiles/file/26491923534.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/3CAf4wW3hvY/uplcv?utm_term=object+oriented+design+principles+head+first+pdfPDF link annotation
    • 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_off0000ebe9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEBE9 17784 bytes
SHA-256: ebc5a008d84686d1277d4114e67bc4bcf75bc52b97991705b48815f4ecbf5963
font_01_sfnt_off00011a5b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11A5B 11196 bytes
SHA-256: 14d9793a3f29be14951f69abc6919dc2c6664555c444ab5bb41d0b8d9830d6e4
font_02_sfnt_off00013409.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13409 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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