Malicious RTF — malware analysis report

Static analysis result for SHA-256 d6daa3deec179460…

MALICIOUS

RTF

5.49 MB First seen: 2023-04-01
MD5: 8c65081cbc51c47f8ec97c98a8645ff0 SHA-1: 85d168e0b6f45b6a5f3e42e7319c78968e199ede SHA-256: d6daa3deec1794602cd5d15d77c4cfba68b90c65c264b9c8754c7aba5ad81d34
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The RTF file contains embedded OLE object data, specifically related to the Equation Editor. Heuristics indicate a critical vulnerability, CVE-2017-11882, which is known to be exploited via crafted RTF documents. The excessive hex data and OLE object activation further support the exploitation of this vulnerability to execute a hidden payload.

Heuristics 5

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Decoded Equation Editor payload + PE critical RTF_EQUATION_EDITOR
    RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~5751KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000004f0.bin
0d55c146b89908bcbc91c4f0e2d7205be4eeb460e709eaf1474c032fea63dea7		 rtf-objdata-decoded RTF \objdata at offset 0x4F0 2875922 bytes

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