RTF / .DOC malware analysis — malicious · 7ac43c074514c0ff

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-22

MD5: ca8680e03c293b5309928fc2702c5681 SHA-1: 87908e11bba5ad0ae34d8358beebc0ceacb81d45 SHA-256: 7ac43c074514c0fffac64bb04f0e86f31652acd089712ef16931cd2cc8cf8eaa

180 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The file is an RTF document containing an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate the exploitation of CVE-2017-11882, which is a known vulnerability allowing for arbitrary code execution when the object is activated. The ".\objupdate" directive forces OLE activation, leading to the execution of the embedded malicious content. No scripts were extracted, but the RTF structure and heuristics strongly suggest a classic exploit delivery mechanism.

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_off00001347.bin` `9acc0e81b494a937639c31e0a3defcb670f5be46ef12d1fa59c6e2947b1a2d73`	rtf-objdata-decoded	RTF \objdata at offset 0x1347	26952 bytes
`objdata_01_off00019fe2.bin` `7271b266ae613b3f0f4a2339cdc62b69633b07c00e19c66830febcf36614100d`	rtf-objdata-decoded	RTF \objdata at offset 0x19FE2	461830 bytes

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