Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 323198f5a6abafa0…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-22
MD5: 7ab6abc412057d3780172e66dcdb2488 SHA-1: 43bff1e31602a02c689b263b799e9e808d0602ee SHA-256: 323198f5a6abafa03d0eae8d58eadafd8620d1c60f7a5c7b78959681cc6abaa0
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains an embedded OLE object specifically identified as an Equation Editor object, triggering heuristics related to CVE-2017-11882. This vulnerability allows for the execution of arbitrary code. The embedded object data, when decoded, contains obfuscated VBScript-like code that appears to attempt to evaluate strings and potentially execute commands, though the full payload is truncated. The primary attack vector is the exploitation of the Equation Editor vulnerability.

Heuristics 5

  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001347.bin
03419f3d969006d1c0a467ee63d9b4c1a8ee9435f641ba731a6f0bb2da3b4815		 rtf-objdata-decoded RTF \objdata at offset 0x1347 26951 bytes
objdata_01_off00019fe0.bin
7271b266ae613b3f0f4a2339cdc62b69633b07c00e19c66830febcf36614100d		 rtf-objdata-decoded RTF \objdata at offset 0x19FE0 461830 bytes

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