RTF / .DOC malware analysis — malicious · 369bdbe8219c53b7

MALICIOUS

RTF / .DOC

1.06 MB First seen: 2022-10-11

MD5: fca8329d1b2cb450f6fa8ed740c9cf9f SHA-1: 7ef2ace8a3b6e46f7fd6b155396219e4955b1bfa SHA-256: 369bdbe8219c53b7a315cf4a34147cd3b9979206e86c6f8243bfbcbd24c20dd5

180 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The critical heuristic firing for RTF_EQUATION_EDITOR and the high confidence firing for CVE_2017_11882_ACTIVATION_RELATED indicate the exploitation of a known Microsoft Office Equation Editor vulnerability. The embedded OLE object data likely contains the malicious payload, which is activated by \objupdate. The presence of VBA code suggests an attempt to download and execute a secondary 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.

Filename	Kind	Source	Size
`objdata_00_off0000129e.bin` `cda9585c7a040a441949bf14a7f58b497847bc28fc03b36b279af98109c3a09a`	rtf-objdata-decoded	RTF \objdata at offset 0x129E	80998 bytes
`objdata_01_off0002ece8.bin` `83d5bb1839df37f7a8edeb2ba75fa5745f7c4929c4a96b9f25135a1ffd60f649`	rtf-objdata-decoded	RTF \objdata at offset 0x2ECE8	187615 bytes

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