Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 802b2341dc036f2e…

MALICIOUS

RTF / .DOC

1.06 MB First seen: 2022-09-29
MD5: c0fc0cb718f006be86c493cd76f20b5f SHA-1: 5039ea0720bbdb64bf1af57fbe309826653cc20a SHA-256: 802b2341dc036f2e94042e2aaef09aa24b3bf07b3b925db5317f8051c29091f5
180 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking T1204.002 Malicious File

The RTF document contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in the Equation Editor. The heuristic firings indicate the presence of an Equation Editor object and its activation via \objupdate, strongly suggesting the execution of arbitrary code. The embedded data appears to contain VBA script intended to read resources from an INI file, likely to download and execute a second-stage payload.

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_off000012b8.bin
ff6517fea3c10d45ccb7e0e9aeac85ecbf4892286b73291e65a8d642588cc600		 rtf-objdata-decoded RTF \objdata at offset 0x12B8 81433 bytes
objdata_01_off0002f082.bin
636022af1c118cbfdb875b9c9e9f1876d2aa6f697aa661a5028ea2cb956d97f9		 rtf-objdata-decoded RTF \objdata at offset 0x2F082 187349 bytes

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