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specify osx-min-version to configure #7

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Mar 26, 2020
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@alfred-landrum alfred-landrum commented Mar 26, 2020

We've had a user report that they can't load any pcaps, and were seeing this error:

Detail: zeek exited with status -1: dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin Referenced from: /Applications/Brim.app/Contents/Resources/app/zdeps/zeek/bin/zeek (which was built for Mac OS X 10.15) Expected in: /usr/lib/libSystem.B.dylib dyld: Symbol not found: ____chkstk_darwin Referenced from: /Applications/Brim.app/Contents/Resources/app/zdeps/zeek/bin/zeek (which was built for Mac OS X 10.15) Expected in: /usr/lib/libSystem.

So we'll build zeek specifying a minimum MacOS version. I've built an executable by hand and asked them to report back if it helps. I'm selecting 10.10 because that's the current minimum for the go & electron versions we're using at the moment.

@alfred-landrum alfred-landrum requested a review from a team March 26, 2020 02:22
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Besides trying to run the resulting binary on an older MacOS version, this can also be verified with otool -l; look for LC_VERSION_MIN_MACOSX:

In the current build, when the minimum isn't set, it's not present:

$ otool -l zeek-10.15 | grep LC_VERSION_MIN_MACOSX -A 3
$

After building with this flag set:

$ otool -l zeek-min-10.10 | grep LC_VERSION_MIN_MACOSX -A 3
      cmd LC_VERSION_MIN_MACOSX
  cmdsize 16
  version 10.10
      sdk 10.15.4
$

@alfred-landrum alfred-landrum merged commit 2f89708 into master Mar 26, 2020
@alfred-landrum alfred-landrum deleted the macos-minimum branch March 26, 2020 15:15
nwt pushed a commit that referenced this pull request Apr 24, 2020
…cket

An attacker can make Zeek crash by posting the KEX packet twice, which
will result in an assertion failure in binpac::datastring::init():

 #0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
 #1  0x00007ffff5196535 in __GI_abort () at abort.c:79
 #2  0x00007ffff519640f in __assert_fail_base (fmt=0x7ffff52f86e0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x1d33530 "!data_",
     file=0x1d33537 "aux/binpac/lib/binpac_bytestring.h", line=108, function=<optimized out>) at assert.c:92
 #3  0x00007ffff51a3b92 in __GI___assert_fail (assertion=0x1d33530 "!data_", file=0x1d33537 "aux/binpac/lib/binpac_bytestring.h",
     line=108, function=0x1d3356c "void binpac::datastring<unsigned char>::init(const T *, int) [T = unsigned char]") at assert.c:101
 #4  0x0000000000c1e970 in binpac::datastring<unsigned char>::init (this=0x608000d609d0, begin=0x603001bdd1d0 "diffie-hellman-group16-sha512", length=29)
     at aux/binpac/lib/binpac_bytestring.h:108
 #5  0x0000000000e9ab60 in binpac::SSH::SSH_Conn::update_kex (this=0x608000d609a0, algs=..., orig=true) at src/analyzer/protocol/ssh/ssh_pac.cc:205
 #6  0x0000000000ea0d06 in binpac::SSH::SSH2_KEXINIT::Parse (this=0x60b000734680,
     t_begin_of_data=0x621000004753 "\200\275\a%\223\023Y8\204t\235\363!\031I.", t_end_of_data=0x621000004b85 "ޭ\276", <incomplete sequence \357>,
     t_context=0x603001bdcc90, t_byteorder=0) at src/analyzer/protocol/ssh/ssh_pac.cc:1598
 #7  0x0000000000e9f8f4 in binpac::SSH::SSH2_Message::Parse (this=0x608000d60ea0,
     t_begin_of_data=0x621000004753 "\200\275\a%\223\023Y8\204t\235\363!\031I.", t_end_of_data=0x621000004b85 "ޭ\276", <incomplete sequence \357>,
     t_context=0x603001bdcc90, t_byteorder=0) at src/analyzer/protocol/ssh/ssh_pac.cc:1326
 #8  0x0000000000e9d7e1 in binpac::SSH::SSH2_Key_Exchange::Parse (this=0x604001779850,
     t_begin_of_data=0x621000004751 "\006\024\200\275\a%\223\023Y8\204t\235\363!\031I.", t_end_of_data=0x621000004b85 "ޭ\276", <incomplete sequence \357>,
     t_context=0x603001bdcc90, t_byteorder=0) at src/analyzer/protocol/ssh/ssh_pac.cc:1210
 #9  0x0000000000e9c981 in binpac::SSH::SSH_Key_Exchange::ParseBuffer (this=0x603001bdccc0, t_flow_buffer=0x608000d60a20, t_context=0x603001bdcc90,
     t_byteorder=0) at src/analyzer/protocol/ssh/ssh_pac.cc:628
 #10 0x0000000000e9c26c in binpac::SSH::SSH_PDU::ParseBuffer (this=0x604001779810, t_flow_buffer=0x608000d60a20, t_context=0x603001bdcc90)
     at src/analyzer/protocol/ssh/ssh_pac.cc:446
 #11 0x0000000000ea6f04 in binpac::SSH::SSH_Flow::NewData (this=0x604001774690, t_begin_of_data=0x62100000474d "",
     t_end_of_data=0x621000004b85 "ޭ\276", <incomplete sequence \357>) at src/analyzer/protocol/ssh/ssh_pac.cc:3071
 #12 0x0000000000e9a38f in binpac::SSH::SSH_Conn::NewData (this=0x608000d609a0, is_orig=true, begin=0x62100000474d "",
     end=0x621000004b85 "ޭ\276", <incomplete sequence \357>) at src/analyzer/protocol/ssh/ssh_pac.cc:63
 #13 0x0000000000e98335 in analyzer::SSH::SSH_Analyzer::DeliverStream (this=0x7fffffffdd40, len=1080, data=0x62100000474d "", orig=true)
     at src/analyzer/protocol/ssh/SSH.cc:68

With assertions turned off, this would "only" be a memory leak.

This commit fixes the vulnerability by freeing and clearing the
`binpac::datastring` before assigning a new value.
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