Malicious RTF — malware analysis report

Static analysis result for SHA-256 71100144ebee61e7…

MALICIOUS

RTF

2.20 MB
MD5: fa1b5195bb3b93f184d2ec7909fe2784 SHA-1: 5ec2bdce9c363b9c9ddfb2125e283c69a158e418 SHA-256: 71100144ebee61e79ef78ec3a88da610c615cc662ba7e92d1a22c31fa791ba4b
220 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object related to CVE-2017-11882, which is a known vulnerability in Microsoft Equation Editor. This vulnerability allows for remote code execution when the object is activated, likely through a objupdate directive. The large amount of hex-encoded data within the OLE object suggests it is used to hide a malicious payload.

Heuristics 5

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact 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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~2301KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000c0.bin
8910a7e83cdf1ed4c3c773aaa64d214ac70580a7407f97f005af8f824cf1ec1e		 rtf-objdata-decoded RTF \objdata at offset 0xC0 920481 bytes

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