fortra/impacket

Unsupported data type on TDS version >=7.2

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#877 建立於 2020年6月9日

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 (2 留言) (0 反應) (0 負責人)Python (12,244 star) (3,421 fork)batch import
enhancementhelp wanted

描述

Configuration

impacket version: 0.9.21 Python version: 3.7.7 Target OS: Ubuntu 18.04

Debug Output With Command String

i.e.
smbexec -debug domain/user:password@127.0.0.1

>>> d = tds.TDS_COLMETADATA(b"\x81\x01\x00\x00\x00\x00\x00\x08\x00\x38\x09\x41\x00\x70\x00\x70\x00\x74\x00\x43\x00\x6f\x00\x6c\x00\x6f\x00\x72\x00")
>>> tds.MSSQL('bla').parseColMetaData(d)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/user/.local/lib/python3.7/site-packages/impacket/tds.py", line 1439, in parseColMetaData
    raise Exception("Unsupported data type: 0x%x" % colType)
Exception: Unsupported data type: 0x8

Additional context

This Column Metadata bytes was taken from pcap of TDS version 7.2.

As far as I understand, the problem is size of field userType:

  • until TDS version 7.1, userType size is 2 bytes.
  • since TDS version 7.2, userType size is 4 bytes.

The code of the library assume userType size is 2 bytes.

貢獻者指南

技術棧
python
領域
backenddatabaseapi
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
1-3 hours
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
Pythonbasic understanding of TDS protocol
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
40
研究方向
The issue is in impacket's tds.py file, specifically in the parseColMetaData method around line 1439. The problem is that the userType field size differs between TDS versions: 2 bytes for versions <7.2 and 4 bytes for versions >=7.2. The code currently always reads 2 bytes. To fix, check the TDS version (likely stored in the MSSQL object) and conditionally read 2 or 4 bytes for userType. Refer to the comments in the issue for more context on the pcap example.
Unsupported data type on TDS version >=7.2 · fortra/impacket#877 | Good First Issue