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Fix hang in DNS analyzer with malformed packet

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(cherry picked from commit dfc9f77b68f6d02d059ade322b9c132e32c26872)
This commit is contained in:
Tim Wojtulewicz 2022-05-27 14:23:04 -07:00
parent 41aa8b2349
commit 9964a46402
4 changed files with 22 additions and 3 deletions
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6
CHANGES
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@ -1,3 +1,9 @@
5.0.0-dev.572 | 2022-06-03 10:31:51 -0700
* Fix hang in DNS analyzer with malformed packet (Tim Wojtulewicz, Corelight)
(cherry picked from commit dfc9f77b68f6d02d059ade322b9c132e32c26872)
5.0.0-dev.571 | 2022-06-03 09:50:45 -0700
* Additional &is_used tags in the Netcontrol and Sumstats frameworks (Christian Kreibich, Corelight)

2
VERSION
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@ -1 +1 @@
5.0.0-dev.571
5.0.0-dev.572

16
src/analyzer/protocol/dns/DNS.cc
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@ -236,6 +236,11 @@ bool DNS_Interpreter::ParseAnswer(detail::DNS_MsgInfo* msg, const u_char*& data,
analyzer->Weird("DNS_truncated_RR_rdlength_lt_len");
return false;
}
else if ( rdlength == 0 && len > 0 )
{
analyzer->Weird("DNS_zero_rdlength");
return false;
}
bool status;
switch ( msg->atype )
@ -690,8 +695,9 @@ bool DNS_Interpreter::ParseRR_EDNS(detail::DNS_MsgInfo* msg, const u_char*& data
analyzer->EnqueueConnEvent(dns_EDNS_addl, analyzer->ConnVal(), msg->BuildHdrVal(),
msg->BuildEDNS_Val());
// parse EDNS options
while ( len > 0 )
// parse EDNS options. length has to be at least 4 to parse out the option
// code and length.
while ( len >= 4 )
{
uint16_t option_code = ExtractShort(data, len);
int option_len = ExtractShort(data, len);
@ -891,6 +897,12 @@ bool DNS_Interpreter::ParseRR_EDNS(detail::DNS_MsgInfo* msg, const u_char*& data
}
}
if ( len > 0 )
{
analyzer->Weird("EDNS_truncated_option");
return false;
}
return true;
}

1
testing/btest/Baseline/scripts.base.protocols.dns.dns-edns-ecs/weird.log
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@ -12,4 +12,5 @@ XXXXXXXXXX.XXXXXX ClEkJM2Vm5giqnMf4h 74.125.73.76 55744 192.168.90.10 53 EDNS_EC
XXXXXXXXXX.XXXXXX C4J4Th3PJpwUYZZ6gc 2a00:1450:4013:c03::10a 46433 2001:470:765b::a25:53 53 EDNS_ECS_invalid_addr_v6_prefix 255 bits F zeek DNS
XXXXXXXXXX.XXXXXX CtPZjS20MLrsMUOJi2 2a00:1450:4013:c06::105 63369 2001:470:765b::a25:53 53 EDNS_ECS_invalid_addr_v6 need 66 bits, have 56 bits F zeek DNS
XXXXXXXXXX.XXXXXX CUM0KZ3MLUfNB0cl11 2a00:1450:400c:c00::106 54430 2001:470:765b::a25:53 53 EDNS_ECS_invalid_option_len - F zeek DNS
XXXXXXXXXX.XXXXXX CUM0KZ3MLUfNB0cl11 2a00:1450:400c:c00::106 54430 2001:470:765b::a25:53 53 EDNS_truncated_option - F zeek DNS
#close XXXX-XX-XX-XX-XX-XX