Malicious RTF — malware analysis report

Static analysis result for SHA-256 21fb581321d09377…

MALICIOUS

RTF

14.1 KB First seen: 2018-07-27
MD5: c06fb2bbf7acebf62bb50645ead495c4 SHA-1: fd742970eeb715d61dd787374627e9b4fad0f15c SHA-256: 21fb581321d09377809c5cfb6ba45c817508d1b7cc4fb3daf3e1f56015184255
200 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 is automatically linked and updated, triggering an exploit for CVE-2017-11882. This exploit is known to deliver a secondary payload, which is likely malicious. The presence of the Ole10Native stream and the specific heuristic firing for CVE-2017-11882 strongly indicate this attack vector.

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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000804.bin rtf-objdata-decoded RTF \objdata at offset 0x804 4141 bytes
SHA-256: 4ff05fa6f5f8af7c8e5db2fd55fbe17949aed7532c01effb259a76a241f8bbfa