win32k!NtGdiEnumFonts System Call Handler Disclosure

vendor:

N/A

by:

Mateusz Jurczyk

7,8

CVSS

HIGH

win32k!NtGdiEnumFonts System Call Handler Disclosure

119

CWE

Product Name: N/A

Affected Version From: N/A

Affected Version To: N/A

Patch Exists: YES

Related CWE: N/A

CPE: N/A

Metasploit: N/A

Other Scripts: N/A

Tags: N/A

CVSS Metrics: N/A

Nuclei References: N/A

Nuclei Metadata: N/A

Platforms Tested: Windows

2017

win32k!NtGdiEnumFonts System Call Handler Disclosure

The win32k!NtGdiEnumFonts system call handler discloses very large portions of uninitialized pool memory to user-mode clients. This issue can be reproduced by running the attached proof-of-concept program on a system with the Special Pools mechanism enabled for win32k.sys. It is then visible that a significant number of the bytes are equal to the markers inserted by Special Pools, and would otherwise contain leftover data that was previously stored in that memory region.

Mitigation:

The Special Pools mechanism should be enabled for win32k.sys.

Source

Exploit-DB raw data:

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1153

We have discovered that the win32k!NtGdiEnumFonts system call handler discloses very large portions of uninitialized pool memory to user-mode clients.

The issue can be reproduced by running the attached proof-of-concept program on a system with the Special Pools mechanism enabled for win32k.sys. Then, it is clearly visible that a significant number of the bytes are equal to the markers inserted by Special Pools, and would otherwise contain leftover data that was previously stored in that memory region. In this case, the marker byte is 0x47 ("G"), and a dump of the initial 512 bytes of output is shown below. A full dump of the output can be found in the attached file.

--- cut ---
00000000: e4 01 00 00 70 01 00 00 04 00 00 00 25 00 00 00 ....p.......%...
00000010: 12 00 00 00 00 00 00 00 00 00 00 00 90 01 00 00 ................
00000020: 00 00 00 ee 03 02 01 31 43 00 6f 00 6e 00 73 00 .......1C.o.n.s.
00000030: 6f 00 6c 00 61 00 73 00 00 00 47 47 47 47 47 47 o.l.a.s...GGGGGG
00000040: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
00000050: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
00000060: 47 47 47 47 47 47 00 00 43 00 6f 00 6e 00 73 00 GGGGGG..C.o.n.s.
00000070: 6f 00 6c 00 61 00 73 00 00 00 47 47 47 47 47 47 o.l.a.s...GGGGGG
00000080: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
00000090: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
000000a0: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
000000b0: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
000000c0: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
000000d0: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
000000e0: 47 47 47 47 47 47 00 00 52 00 65 00 67 00 75 00 GGGGGG..R.e.g.u.
000000f0: 6c 00 61 00 72 00 00 00 47 47 47 47 47 47 47 47 l.a.r...GGGGGGGG
00000100: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
00000110: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
00000120: 47 47 47 47 47 47 00 00 43 00 65 00 6e 00 74 00 GGGGGG..C.e.n.t.
00000130: 72 00 61 00 6c 00 20 00 45 00 75 00 72 00 6f 00 r.a.l. .E.u.r.o.
00000140: 70 00 65 00 61 00 6e 00 00 00 47 47 47 47 47 47 p.e.a.n...GGGGGG
00000150: 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 47 GGGGGGGGGGGGGGGG
00000160: 47 47 47 47 47 47 47 47 64 76 00 08 00 00 00 00 GGGGGGGGdv......
00000170: 47 47 47 47 00 ff 01 02 25 00 00 00 1d 00 00 00 GGGG....%.......
00000180: 08 00 00 00 05 00 00 00 00 00 00 00 11 00 00 00 ................
00000190: 23 00 00 00 90 01 00 00 00 00 00 00 60 00 00 00 #...........`...
000001a0: 60 00 00 00 00 00 ff fe 01 00 02 00 00 00 00 36 `..............6
000001b0: ee 47 47 47 40 00 24 00 00 08 00 00 5e 09 00 00 .GGG@.$.....^...
000001c0: 66 04 00 00 ff 02 00 e1 ff fc 00 40 09 00 00 00 f..........@....
000001d0: 00 00 00 00 9f 01 00 60 00 00 d7 df 61 6c 00 08 .......`....al..
000001e0: 00 00 00 00 e4 01 00 00 70 01 00 00 04 00 00 00 ........p.......
000001f0: 25 00 00 00 12 00 00 00 00 00 00 00 00 00 00 00 %...............
--- cut ---


Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/42214.zip