CVE-2015-4481 : Detail

CVE-2015-4481

0.23%V4
Local
2015-08-15
23h00 +00:00
2017-09-16
07h57 +00:00
CVE.org
NVD
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CVE Descriptions

Race condition in the Mozilla Maintenance Service in Mozilla Firefox before 40.0 and Firefox ESR 38.x before 38.2 on Windows allows local users to write to arbitrary files and consequently gain privileges via vectors involving a hard link to a log file during an update.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Metrics

Metrics Score Severity CVSS Vector Source
V2 3.3 AV:L/AC:M/Au:N/C:N/I:P/A:P nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 37925

Publication date : 2015-08-20 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://code.google.com/p/google-security-research/issues/detail?id=427&can=1 Mozilla Maintenance Service: Log File Overwrite Elevation of Privilege Platform: Windows Version: Mozilla Firefox 38.0.5 Class: Elevation of Privilege Summary: The maintenance service creates a log file in a user writable location. It’s possible to change the log file to a hardlink to another file to cause file corruption or elevation of privilege. Description: When the maintenance service starts it creates a log file under c:\programdata\mozilla\logs. This is done in maintenanceservice.cpp/SvcMain. This directory it creates the file in has fairly permissive permissions which allows a normal user to create new files underneath that directory. It’s possible to race the creation of the log file during the service initialization to drop a hardlink to an existing file on the same drive (which is probably the system drive) which when opened by the maintenance service running as local system will cause the file to be overwritten by the log data. At the very least this would corrupt the target file, however as the user has some control over bits of the contents, such as the updater path, it’s possible to get some user controlled contents in there. This might be used to elevate privileges by overwriting a script file which has a permissive parser, such as powershell, batch or HTA which subsequently gets executed by a privileged process. The only slight difficulty in exploitation is that the user cannot directly delete the log file to replace it with a hardlink. However this isn’t a significant issue as before opening the log file the service backs up the log to a new name leaving the directory entry for “maintenanceservice.log” free. Therefore there’s a race condition between the log file being moved out of the way and the new log file being created. So to exploit this you perform the following operations: 1. Start a thread which creates a hard link in the log directory to the file you want to overwrite. Repeat until successful. 2. In another thread start the service passing the arbitrary content you want to insert as the path to the updater file A similar vulnerability exists in the update.status handling, for example in WriteStatusFailure which will write update.status to any location you specify. You can use a hardlink to force the file to be overwritten. In this case this would only cause file corruption as the user has no real control on the contents. If I could recommend fixes either make the logs directory writable only by administrators or use CopyFile instead of MoveFile when backing up the previous logs. I would not recommend trying to do anything like inspecting the file for hardlinks or similar. Proof of Concept: I’ve attached a proof of concept, it’s written in C#. You’ll need to compile it with the C# csc compiler. NOTE: you might need to run this on a multi-core machine to stand a chance of winning the race. 1) Compile the PoC 2) Execute the PoC passing the name of a file you want to overwrite on the command line 3) Program should run and print Done if successful Expected Result: The log file is created as normal Observed Result: The target file has been overwritten with the contents of the log file Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/37925.zip

Products Mentioned

Configuraton 0

Mozilla>>Firefox >> Version To (including) 39.0.3

Mozilla>>Firefox >> Version 38.0

Mozilla>>Firefox >> Version 38.0.1

Mozilla>>Firefox >> Version 38.0.5

Mozilla>>Firefox >> Version 38.1.0

Microsoft>>Windows >> Version *

Configuraton 0

Opensuse>>Opensuse >> Version 13.1

Opensuse>>Opensuse >> Version 13.2

Configuraton 0

Oracle>>Solaris >> Version 11.3

References

https://www.exploit-db.com/exploits/37925/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securitytracker.com/id/1033247
Tags : vdb-entry, x_refsource_SECTRACK
https://security.gentoo.org/glsa/201605-06
Tags : vendor-advisory, x_refsource_GENTOO
http://www.securitytracker.com/id/1033372
Tags : vdb-entry, x_refsource_SECTRACK