ESB-2017.3131 - [FreeBSD] kernel: Access privileged data - Existing account 2017-12-07

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2017.3131
                  Kernel data leak via ptrace(PT_LWPINFO)
                              7 December 2017

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           kernel
Publisher:         FreeBSD
Operating System:  FreeBSD
Impact/Access:     Access Privileged Data -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2017-1086  

Reference:         ESB-2017.2911

Original Bulletin: 
   link: http://www.vuxml.org/freebsd/34a3f9b5-dab3-11e7-b5af-a4badb2f4699.html

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FreeBSD -- Kernel data leak via ptrace(PT_LWPINFO)

Affected packages

11.1 <= FreeBSD-kernel < 11.1_4

11.0 <= FreeBSD-kernel < 11.0_15

10.4 <= FreeBSD-kernel < 10.4_3

10.3 <= FreeBSD-kernel < 10.3_24

Details

VuXML ID 34a3f9b5-dab3-11e7-b5af-a4badb2f4699

Discovery 2017-11-15

Entry 2017-12-06

Problem Description:

Not all information in the struct ptrace_lwpinfo is relevant for the state of
any thread, and the kernel does not fill the irrelevant bytes or short 
strings. Since the structure filled by the kernel is allocated on the kernel 
stack and copied to userspace, a leak of information of the kernel stack of 
the thread is possible from the debugger.

Impact:

Some bytes from the kernel stack of the thread using ptrace(PT_LWPINFO) call 
can be observed in userspace.

References

CVE Name CVE-2017-1086

FreeBSD Advisory SA-17:08.ptrace

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