Malicious RTF — malware analysis report

Static analysis result for SHA-256 3664ad1886e4ccac…

MALICIOUS

RTF

2.23 MB
MD5: 57c7de42cf38103ead369464079a6b04 SHA-1: 3308e3144a3fea2e20b5a0ef8d80e5f503e942ef SHA-256: 3664ad1886e4ccac07d9acefafd983f040bf9388a4fb906ac4d87fce26192154
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF file contains embedded OLE objects, specifically triggering critical heuristics related to Equation Editor and CVE-2017-11882. The ".objupdate" directive forces OLE activation, indicating an attempt to exploit this vulnerability. The decoded object data suggests the execution of a script, likely to download and run a secondary payload. The presence of 'Client.vbs' and script fragments related to checking disk space and executing code further supports this attack pattern.

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
7881b595f72cf4418e9d75d8441cd5916de18e1ff924d7f5d97a10ab5d02d769		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27091 bytes
objdata_01_off0001c967.bin
fba5628a71970a3b0db2d58570b2520c14bb66d487fa55e6c0938c31d01dd855		 rtf-objdata-decoded RTF \objdata at offset 0x1C967 479408 bytes

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