Malicious RTF — malware analysis report

Static analysis result for SHA-256 c8ce04bdacb20c3f…

MALICIOUS

RTF

502.1 KB First seen: 2019-08-04
MD5: a98659b66098b3041fe336c573fdec0e SHA-1: e817b244287ea956470dfb68d95a87ca77e78eb7 SHA-256: c8ce04bdacb20c3f4d30c19cfaccb21fddb2ceaf1ef35263d9edbc2ba9099540
424 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an RTF file that leverages CVE-2017-8570 by embedding OLE objects with a composite moniker. This technique is known to drop and execute a second-stage payload, likely a script, as indicated by the 'drops SCT script' heuristic and the presence of extracted binary artifacts. The ClamAV detection of 'Win.Packer.MalwareCrypter-6642003-1' further supports its malicious nature.

Heuristics 10

  • Composite Moniker — CVE-2017-8570 (drops SCT script) critical CVE related CVE_2017_8570
    RTF \objdata decodes to OLE data containing the Composite Moniker — CVE-2017-8570 (drops SCT script) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • ClamAV: Win.Packer.MalwareCrypter-6642003-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Packer.MalwareCrypter-6642003-1
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 7 \objdata section(s) — embedded OLE objects
  • OlePres presentation stream in RTF OLE object medium RTF_OLEPRES_STREAM
    RTF contains an embedded OLE object with an OlePres presentation stream. OlePres is an OLE presentation marker and is not enough on its own to identify CVE-2025-21298.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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://nsis.sf.net/NSIS_Error In RTF body

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000a57.bin rtf-objdata-decoded RTF \objdata at offset 0xA57 400 bytes
SHA-256: fa79b00817f7495218632b8aca05100fc72b724a674512e970aa8642ceaa44bc
objdata_01_off00000daa.bin rtf-objdata-decoded RTF \objdata at offset 0xDAA 245574 bytes
SHA-256: 4d33b9f92254fbd6dfa736f64250cc556c42f56d74af0b1bc6d919a5394066ef
Detection
ClamAV: Win.Packer.MalwareCrypter-6642003-1
Obfuscation or payload: likely
Carved artifact entropy is 7.78, consistent with packed or encrypted content.
objdata_02_off00078c74.bin rtf-objdata-decoded RTF \objdata at offset 0x78C74 320 bytes
SHA-256: 1ce621befe3e2fb260f21f4ff69302dde2bd2b3d8f9bd8f0ac8efafe1c507f86
objdata_03_off00078f28.bin rtf-objdata-decoded RTF \objdata at offset 0x78F28 607 bytes
SHA-256: 3ca384b5b1acf693ecd57ffaff8e9ef08b574bfc032f664fa26e1e38a32da9dd
objdata_04_off0007941c.bin rtf-objdata-decoded RTF \objdata at offset 0x7941C 915 bytes
SHA-256: 676d008f0fa78b6755968751f92bce27b271c9f67cfbadbeb87fa350109f3e88
objdata_05_off00079ba8.bin rtf-objdata-decoded RTF \objdata at offset 0x79BA8 2633 bytes
SHA-256: 9596108877b1101d0c2a2487ed90b66f4a8a9488a5cc78d8e14d0ee1b47095da
objdata_06_off0007b0b2.bin rtf-objdata-decoded RTF \objdata at offset 0x7B0B2 4679 bytes
SHA-256: 8bf8a5d8ef4f4cad2a54df858afa1745c6251ce5031dc2b72e0cd9c554cd899d

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