Malicious RTF — malware analysis report

Static analysis result for SHA-256 b833b34be943426f…

MALICIOUS

RTF

19.3 KB First seen: 2018-09-04
MD5: 08c11aa1cad97610aa6cc15cb3f6d935 SHA-1: 3b3094061820205e31e70308c8bf9cb2217079bb SHA-256: b833b34be943426f04f561bb7adffca207934ba54b094ddd893568ce8552af86
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that leverages the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit is designed to execute arbitrary code, likely leading to the download and execution of a secondary payload. The presence of the Ole10Native stream and the objupdate heuristic strongly indicate an attempt at OLE object activation for exploitation.

Heuristics 5

  • Equation Editor Ole10Native payload — CVE-2017-11882 likely critical CVE likely CVE_2017_11882_EQUATION_OLE10NATIVE
    RTF decodes to an activated Microsoft Equation 3.0 OLE storage whose payload is a high-entropy Ole10Native stream rather than normal Equation Native/MTEF data. This is a weaponized Equation Editor RCE delivery shape consistent with CVE-2017-11882/CVE-2018-0802.
  • Ole10Native stream in RTF OLE object high CVE related RTF_OLE10NATIVE_STREAM
    RTF contains an embedded OLE object with an Ole10Native stream. This is a strong payload-container signal and is related to Word/OLE exploit delivery, but it is not specific enough on its own to assign a CVE.
  • \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 1 \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_off00001675.bin rtf-objdata-decoded RTF \objdata at offset 0x1675 4658 bytes
SHA-256: 9732820513d275a98f7165cc22f4c45e70b1a6ec27919099ec67d38db670f3e2