Malicious RTF — malware analysis report

Static analysis result for SHA-256 a0a7e8e13b879f00…

MALICIOUS

RTF

1.84 MB
MD5: 8915d3f97cbf4f59390db72efd82c4b3 SHA-1: 7163df646762008dfc240ef76813698fa81209d6 SHA-256: a0a7e8e13b879f0031dcca436fbd0819b02cd1149e8c67f0e95974856a001f4c
240 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object with a ProgID indicative of Equation Editor, triggering the CVE-2017-11882 exploit. This exploit is known to facilitate the execution of arbitrary code, likely to download and run a secondary payload. The presence of large hex-encoded data blocks within the OLE object further suggests the hiding of such a payload.

Heuristics 6

  • 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 ~1931KB 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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000009d.bin
807957972c9e0c469228392af0bc5e63fd55a278d354bf9d38f2155f0883bca0		 rtf-objdata-decoded RTF \objdata at offset 0x9D 966008 bytes

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