Win.Trojan.Myxah-7541011-0 — RTF malware analysis

Static analysis result for SHA-256 90a912b2581e448e…

MALICIOUS

RTF

611.2 KB First seen: 2019-02-20
MD5: a73526b4b8b42ada7c2255ccb6cf7edf SHA-1: 76f90466c0f8b78c7ded3a7b7b960ec87b1f6b92 SHA-256: 90a912b2581e448e3bc6248e5abb6f313e010f0664e5758e983824bd47b815be
400 Risk Score

Malware Insights

Win.Trojan.Myxah-7541011-0 · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains multiple indicators of exploiting the Equation Editor vulnerability (CVE-2017-8570), including Composite Moniker and OLE object data. This exploit is known to drop a script, likely SCT, which is then executed. The ClamAV detection confirms this as Win.Trojan.Myxah-7541011-0, a known trojan.

Heuristics 8

  • 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.Trojan.Myxah-7541011-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Trojan.Myxah-7541011-0
  • \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.
  • Suspicious extracted artifact high 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.
  • 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.

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000002c.bin rtf-objdata-decoded RTF \objdata at offset 0x2C 1147 bytes
SHA-256: 367db34baa4e63d141e8bf2d2e510e45b450630b97dc5700ab182d8a23764eea
objdata_01_off00000951.bin rtf-objdata-decoded RTF \objdata at offset 0x951 302082 bytes
SHA-256: c89178f56d5f545bdf40ca38344ec1f0cf7012fdf4a28b3f2e2d49e84cf55798
Detection
ClamAV: Win.Trojan.Myxah-7541011-0
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.
objdata_02_off0009418f.bin rtf-objdata-decoded RTF \objdata at offset 0x9418F 423 bytes
SHA-256: ac2bec25d6539862937bac512ba7be5f3b5fed71c22723d4fde9699f30a14298
objdata_03_off0009450d.bin rtf-objdata-decoded RTF \objdata at offset 0x9450D 1225 bytes
SHA-256: 8b64e467529c34408c66bd804a2e89a2a83b355be81c3fe39270ee3174062744
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): cscript //nologo %vbs%
objdata_04_off00094f02.bin rtf-objdata-decoded RTF \objdata at offset 0x94F02 2633 bytes
SHA-256: 8b52b981393201c0306debe097c2c356eb54ab68ce0bdbf8cf42fe0426e2aa24
objdata_05_off00096418.bin rtf-objdata-decoded RTF \objdata at offset 0x96418 4679 bytes
SHA-256: c6091ca50903e5fce8352e9a3e94b1b74bfe48e8629006dbcf68849edb375716

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