RTF malware analysis — malicious · e4d58b32c395f7ba

MALICIOUS

RTF

1.08 MB First seen: 2022-09-05

MD5: eda0500ddb09822622eee531bc4cb4e6 SHA-1: bdcf4c1442cae10687a079845f093ad7395bef44 SHA-256: e4d58b32c395f7ba9531bdd14827127faeb1da1b9cd59d0acabf9e3fa2b14e9f

180 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains multiple heuristics indicating the exploitation of CVE-2017-11882 through an embedded Equation Editor object. The ".objupdate" directive forces the activation of this embedded object, which is a known method for arbitrary code execution. The presence of OLE object data further supports this attack vector.

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_off00001291.bin` `87d35072399973c2b75d40e5176347e95a78bb4455e687ad64b32fb3ce211385`	rtf-objdata-decoded	RTF \objdata at offset 0x1291	81837 bytes
`objdata_01_off00033115.bin` `e1fc1a4c0e67e69e3fb71023b7446271b7980a05bfadf3f1c66142aaf4530e1c`	rtf-objdata-decoded	RTF \objdata at offset 0x33115	187172 bytes

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