Malicious PDF — malware analysis report

Static analysis result for SHA-256 831c21eb6f895dd4…

MALICIOUS

PDF

78.5 KB Created: 2021-09-15 11:29:48 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-26
MD5: 06a358cdf7a5d8ea4e655db5fef4e7b1 SHA-1: a81ff3f883a310529e29c3de3a6142e9295805b4 SHA-256: 831c21eb6f895dd47d6daedbf3b89d29b8aaaaa6b2419f0e720c199c38e9ce7f
156 Risk Score

Malware Insights

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

The file was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. Static analysis revealed numerous embedded URLs, many pointing to compromised WordPress sites or disposable domains, characteristic of a link farm used for phishing or malware delivery. The PDF structure and the presence of link farms suggest it's designed to lure users to external malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9982

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://crewmak.ru/uplcv?utm_term=second+order+low+pass+filter+equation PDF link annotation
    • http://baaningdoi.com/file_media/file_image/file/27535630419.pdfIn PDF document text
    • http://www.dadosefatos.net.br/wp-content/plugins/formcraft/file-upload/server/content/files/16134435ee0ecc---11314925699.pdfIn PDF document text
    • http://truhlarstvisollner.cz/data/file/tukiwobifotafojaza.pdfIn PDF document text
    • https://deltaguvenlik.net/userfiles/file/fulelazugawujamok.pdfIn PDF document text
    • https://www.goldenplanet.dk/wp-content/plugins/formcraft/file-upload/server/content/files/161404d1714065---27048548164.pdfIn PDF document text
    • http://elisa5888.com/shopadmin/upload/files/82899433352.pdfIn PDF document text
    • https://nikunjfoundation.org/ckfinder/userfiles/files/zinonumibubumuto.pdfIn PDF document text
    • http://tlxzkj.com/uploads/file/110110042868.pdfIn PDF document text
    • https://gberwanda.com/gbe/useruploads/blogs/files/71777384451.pdfIn PDF document text
    • https://securitydm.com/slicice/file/veziwipusetenujum.pdfIn PDF document text
    • http://slkuang.com/v15/Upload/file/20219121231145642.pdfIn PDF document text
    • https://fermuar.com/wp-content/plugins/formcraft/file-upload/server/content/files/161347e09ec982---12938887065.pdfIn PDF document text
    • http://al-bandak.com/userfiles/file/39768620026.pdfIn PDF document text
    • http://jowinbio.com/upload/files/202109060524463568.pdfIn PDF document text
    • https://cuatudongsaigon.net/uploads/files/balexurevuwivegemitid.pdfIn PDF document text
    • https://morganmethod.com/ci/userfiles/files/namotaketodarelokizawex.pdfIn PDF document text
    • http://energcomb.net/cms_enercomb/sgi_userfiles/userfiles/files/52946081544.pdfIn PDF document text
    • http://tongchangkj.com/uploadfile/file///2021090409552358.pdfIn PDF document text
    • http://sarljarry.com/userfiles/file/15664419509.pdfIn PDF document text
    • http://toyotarent.tw/FileData/ckfinder/files/20210902_4299083DAD484297.pdfIn PDF document text
    • http://jingyitech.com/uploadfile/45249539309.pdfIn PDF document text
    • https://glory-aqua.com/userfiles/file/51916251812.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_off0000cc60.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCC60 18236 bytes
SHA-256: 7c684189f89dfd3d4a5a8ee6a24b970e1a43e41ec386437bbdcf0dd52da0f624
font_01_sfnt_off0000fab7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFAB7 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off000112ce.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x112CE 11020 bytes
SHA-256: 225feeeab21b12b5924d87a6540a5aafb7fead2a6be4d0fd7bbed422ac4e4efd