CVE-2015-0002 : Détail

CVE-2015-0002

A01-Broken Access Control
0.04%V3
Local
2015-01-13
21h00 +00:00
2018-10-12
17h57 +00:00
CVE.org
NVD
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Descriptions du CVE

The AhcVerifyAdminContext function in ahcache.sys in the Application Compatibility component in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 does not verify that an impersonation token is associated with an administrative account, which allows local users to gain privileges by running AppCompatCache.exe with a crafted DLL file, aka MSRC ID 20544 or "Microsoft Application Compatibility Infrastructure Elevation of Privilege Vulnerability."

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-264 Category : Permissions, Privileges, and Access Controls
Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V2 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C nvd@nist.gov

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
EPSS First.org

Informations sur l'Exploit

Exploit Database EDB-ID : 35661

Date de publication : 2014-12-31 23h00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

# Source: https://code.google.com/p/google-security-research/issues/detail?id=118#c1 # Exploit-DB Mirror: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/35661-poc.zip Platform: Windows 8.1 Update 32/64 bit (No other OS tested) On Windows 8.1 update the system call NtApphelpCacheControl (the code is actually in ahcache.sys) allows application compatibility data to be cached for quick reuse when new processes are created. A normal user can query the cache but cannot add new cached entries as the operation is restricted to administrators. This is checked in the function AhcVerifyAdminContext. This function has a vulnerability where it doesn't correctly check the impersonation token of the caller to determine if the user is an administrator. It reads the caller's impersonation token using PsReferenceImpersonationToken and then does a comparison between the user SID in the token to LocalSystem's SID. It doesn't check the impersonation level of the token so it's possible to get an identify token on your thread from a local system process and bypass this check. For this purpose the PoC abuses the BITS service and COM to get the impersonation token but there are probably other ways. It is just then a case of finding a way to exploit the vulnerability. In the PoC a cache entry is made for an UAC auto-elevate executable (say ComputerDefaults.exe) and sets up the cache to point to the app compat entry for regsvr32 which forces a RedirectExe shim to reload regsvr32.exe. However any executable could be used, the trick would be finding a suitable pre-existing app compat configuration to abuse. It's unclear if Windows 7 is vulnerable as the code path for update has a TCB privilege check on it (although it looks like depending on the flags this might be bypassable). No effort has been made to verify it on Windows 7. NOTE: This is not a bug in UAC, it is just using UAC auto elevation for demonstration purposes. The PoC has been tested on Windows 8.1 update, both 32 bit and 64 bit versions. I'd recommend running on 32 bit just to be sure. To verify perform the following steps: 1) Put the AppCompatCache.exe and Testdll.dll on disk 2) Ensure that UAC is enabled, the current user is a split-token admin and the UAC setting is the default (no prompt for specific executables). 3) Execute AppCompatCache from the command prompt with the command line "AppCompatCache.exe c:\windows\system32\ComputerDefaults.exe testdll.dll". 4) If successful then the calculator should appear running as an administrator. If it doesn't work first time (and you get the ComputerDefaults program) re-run the exploit from 3, there seems to be a caching/timing issue sometimes on first run.

Products Mentioned

Configuraton 0

Microsoft>>Windows_7 >> Version -

Microsoft>>Windows_8 >> Version -

Microsoft>>Windows_8.1 >> Version -

Microsoft>>Windows_rt >> Version -

Microsoft>>Windows_rt_8.1 >> Version -

Microsoft>>Windows_server_2008 >> Version r2

Microsoft>>Windows_server_2012 >> Version -

Microsoft>>Windows_server_2012 >> Version r2

    Références

    http://www.securityfocus.com/bid/71972
    Tags : vdb-entry, x_refsource_BID
    http://secunia.com/advisories/61277
    Tags : third-party-advisory, x_refsource_SECUNIA