Malicious RTF — malware analysis report

Static analysis result for SHA-256 47d809d66cdefb4f…

MALICIOUS

RTF

2.28 MB First seen: 2021-10-14
MD5: 592bc9e6ba369a8c9e5933c21ebb48cc SHA-1: 4d03b2f60f430e321c704dadb6ed1043a739212b SHA-256: 47d809d66cdefb4fc4816f3bceff66e21e8a42de61dafff1fd5f5c43fd0b4b84
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of exploitation for CVE-2017-11882, specifically related to the Equation Editor. The presence of \objdata and \objupdate directives, along with the decoded object data, strongly suggests that this vulnerability is being leveraged to achieve code execution. The truncated document body content does not provide further context on the specific lure, but the exploit itself is the primary indicator of malicious intent.

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_off00001202.bin rtf-objdata-decoded RTF \objdata at offset 0x1202 41918 bytes
SHA-256: 3d1ca436744b77e247f775e67d7f839c8ff262b299c4154070b9f3831f9bd82b
objdata_01_off0002e257.bin rtf-objdata-decoded RTF \objdata at offset 0x2E257 476431 bytes
SHA-256: ab8190dca09da6ff1dca4796336845f61c912c780626e8cf56ac21aee774da20

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