[CVE-2021-25216] ZDI-CAN-13347: A second vulnerability in BIND's GSSAPI security policy negotiation can be targeted by a buffer overflow attack
CVE-specific actions
- Assign a CVE identifier
- Determine CVSS score
- Determine the range of BIND versions affected (including the Subscription Edition)
- Determine whether workarounds for the problem exists
-
Prepare a detailed description of the problem which should include the following by default:
- instructions for reproducing the problem (a system test is good enough)
- explanation of code flow which triggers the problem (a system test is not good enough)
-
Prepare a private merge request containing the following items in separate commits:
- a test for the issue (may be moved to a separate merge request for deferred merging)
- a fix for the issue
- documentation updates (
CHANGES, release notes, anything else applicable)
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- Ensure the documentation changes introduced by the merge request addressing the problem are reviewed by Support and Marketing staff
- Prepare backports of the merge request addressing the problem for all affected (and still maintained) BIND branches (backporting might affect the issue's scope and/or description)
- Prepare a standalone patch for the last stable release of each affected (and still maintained) BIND branch
Release-specific actions
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-
Reserve a block of
CHANGESplaceholders once the complete set of vulnerabilities fixed in a given release cycle is determined -
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security-*branches in CVE identifier order
CVSS
8.1: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
ABSTRACT
Trend Micro's Zero Day Initiative has identified a vulnerability affecting the following products: ISC - BIND
VULNERABILITY DETAILS
- Version tested:9.16.13
- Installer file:https://downloads.isc.org/isc/bind9/9.16.13/bind-9.16.13.tar.xz
- Platform tested:debian-10.8.0-i386-netinst
Analysis
integer overflow exist in der_get_oid() and leads to a wild-copy
it affected 32-bit onlylib/dns/spnego.c
der_get_oid(const unsigned char *p, size_t len, oid *data, size_t *size) {
int n;
size_t oldlen = len;
data->components = NULL;
data->length = 0;
if (len < 1U) {
return (ASN1_OVERRUN);
}
[1] data->components = malloc((len + 1) * sizeof(*data->components));
...
}On 32 bit platforms 'len' is unsigned integer. On line #1 integer overflow occurs if we set 'len' to 0x40000000, thus small buffer will be allocated. Later it will be overwritten in oid decoding loop
debug log
Thread 2 "isc-net-0000" hit Breakpoint 2, 0x00d4dc9e in der_get_oid ()
1: x/i $pc
=> 0xd4dc9e <der_get_oid+171>: add eax,0x1
(gdb) i r $eax
eax 0x40000000 1073741824
(gdb) si
0x00d4dca1 in der_get_oid ()
1: x/i $pc
=> 0xd4dca1 <der_get_oid+174>: shl eax,0x2
(gdb) si
0x00d4dca4 in der_get_oid ()
1: x/i $pc
=> 0xd4dca4 <der_get_oid+177>: sub esp,0xc
(gdb) si
0x00d4dca7 in der_get_oid ()
1: x/i $pc
=> 0xd4dca7 <der_get_oid+180>: push eax
(gdb) si
0x00d4dca8 in der_get_oid ()
1: x/i $pc
=> 0xd4dca8 <der_get_oid+181>: call 0x5aa260 <malloc@plt>
(gdb) i r $eax
eax 0x4 4 // integer overflowed
(gdb) bt
#0 0x00d4dca8 in der_get_oid ()
#1 0x00d4f03a in decode_oid ()
#2 0x00d45878 in decode_MechType ()
#3 0x00d46108 in decode_MechTypeList ()
#4 0x00d478c0 in decode_NegTokenInit ()
#5 0x00d4c117 in gss_accept_sec_context_spnego ()
#6 0x00d0530a in dst_gssapi_acceptctx ()
#7 0x00b89bc8 in process_gsstkey ()
#8 0x00b8c332 in dns_tkey_processquery ()
#9 0x00712d33 in ns_query_start ()
#10 0x006998ed in ns.client_request ()
#11 0x00e17092 in isc.nm_async_readcb ()
#12 0x00e166c2 in isc.nm_readcb ()
#13 0x00e4266e in processbuffer ()
#14 0x00e4a2f5 in process_sock_buffer ()
#15 0x00e43038 in read_cb ()
#16 0xb740a727 in ?? () from /lib/i386-linux-gnu/libuv.so.1
#17 0xb740b2b7 in ?? () from /lib/i386-linux-gnu/libuv.so.1
#18 0xb7410468 in uv.io_poll () from /lib/i386-linux-gnu/libuv.so.1
#19 0xb7401146 in uv_run () from /lib/i386-linux-gnu/libuv.so.1
#20 0x00e068e7 in nm_thread ()
#21 0x00e9c1e0 in isc.trampoline_run ()
#22 0xb793d321 in ?? () from /lib/i386-linux-gnu/libasan.so.5
#23 0xb73cdfd2 in start_thread (arg=<optimized out>) at pthread_create.c:486
#24 0xb72b96d6 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108ASAN report
=================================================================
==6064==ERROR: AddressSanitizer: heap-buffer-overflow on address 0xb4a23154 at pc 0x00d4de48 bp 0xb26f8a38 sp 0xb26f8a2c
WRITE of size 4 at 0xb4a23154 thread T1
#0 0xd4de47 in der_get_oid (/var/bind/sbin/named+0x868e47)
#1 0xd4f039 in decode_oid (/var/bind/sbin/named+0x86a039)
#2 0xd45877 in decode_MechType (/var/bind/sbin/named+0x860877)
#3 0xd46107 in decode_MechTypeList (/var/bind/sbin/named+0x861107)
#4 0xd478bf in decode_NegTokenInit (/var/bind/sbin/named+0x8628bf)
#5 0xd4c116 in gss_accept_sec_context_spnego (/var/bind/sbin/named+0x867116)
#6 0xd05309 in dst_gssapi_acceptctx (/var/bind/sbin/named+0x820309)
#7 0xb89bc7 in process_gsstkey (/var/bind/sbin/named+0x6a4bc7)
#8 0xb8c331 in dns_tkey_processquery (/var/bind/sbin/named+0x6a7331)
#9 0x712d32 in ns_query_start (/var/bind/sbin/named+0x22dd32)
#10 0x6998ec in ns__client_request (/var/bind/sbin/named+0x1b48ec)
#11 0xe17091 in isc__nm_async_readcb (/var/bind/sbin/named+0x932091)
#12 0xe166c1 in isc__nm_readcb (/var/bind/sbin/named+0x9316c1)
#13 0xe4266d in processbuffer (/var/bind/sbin/named+0x95d66d)
#14 0xe4a2f4 in process_sock_buffer (/var/bind/sbin/named+0x9652f4)
#15 0xe43037 in read_cb (/var/bind/sbin/named+0x95e037)
#16 0xb740a726 (/lib/i386-linux-gnu/libuv.so.1+0x17726)
#17 0xb740b2b6 (/lib/i386-linux-gnu/libuv.so.1+0x182b6)
#18 0xb7410467 in uv__io_poll (/lib/i386-linux-gnu/libuv.so.1+0x1d467)
#19 0xb7401145 in uv_run (/lib/i386-linux-gnu/libuv.so.1+0xe145)
#20 0xe068e6 in nm_thread (/var/bind/sbin/named+0x9218e6)
#21 0xe9c1df in isc__trampoline_run (/var/bind/sbin/named+0x9b71df)
#22 0xb793d320 (/lib/i386-linux-gnu/libasan.so.5+0x4a320)
#23 0xb73cdfd1 in start_thread /build/glibc-Stc26X/glibc-2.28/nptl/pthread_create.c:486
#24 0xb72b96d5 in __clone (/lib/i386-linux-gnu/libc.so.6+0xfa6d5)
0xb4a23154 is located 0 bytes to the right of 4-byte region [0xb4a23150,0xb4a23154)
allocated by thread T1 here:
#0 0xb79de5d4 in __interceptor_malloc (/lib/i386-linux-gnu/libasan.so.5+0xeb5d4)
#1 0xd4dcac in der_get_oid (/var/bind/sbin/named+0x868cac)
#2 0xd4f039 in decode_oid (/var/bind/sbin/named+0x86a039)
#3 0xd45877 in decode_MechType (/var/bind/sbin/named+0x860877)
#4 0xd46107 in decode_MechTypeList (/var/bind/sbin/named+0x861107)
#5 0xd478bf in decode_NegTokenInit (/var/bind/sbin/named+0x8628bf)
#6 0xd4c116 in gss_accept_sec_context_spnego (/var/bind/sbin/named+0x867116)
#7 0xd05309 in dst_gssapi_acceptctx (/var/bind/sbin/named+0x820309)
#8 0xb89bc7 in process_gsstkey (/var/bind/sbin/named+0x6a4bc7)
#9 0xb8c331 in dns_tkey_processquery (/var/bind/sbin/named+0x6a7331)
#10 0x712d32 in ns_query_start (/var/bind/sbin/named+0x22dd32)
#11 0x6998ec in ns__client_request (/var/bind/sbin/named+0x1b48ec)
#12 0xe17091 in isc__nm_async_readcb (/var/bind/sbin/named+0x932091)
#13 0xe166c1 in isc__nm_readcb (/var/bind/sbin/named+0x9316c1)
#14 0xe4266d in processbuffer (/var/bind/sbin/named+0x95d66d)
#15 0xe4a2f4 in process_sock_buffer (/var/bind/sbin/named+0x9652f4)
#16 0xe43037 in read_cb (/var/bind/sbin/named+0x95e037)
#17 0xb740a726 (/lib/i386-linux-gnu/libuv.so.1+0x17726)
Thread T1 created by T0 here:
#0 0xb79c6b50 in pthread_create (/lib/i386-linux-gnu/libasan.so.5+0xd3b50)
#1 0xed85a5 in isc_thread_create (/var/bind/sbin/named+0x9f35a5)
#2 0xe03a94 in isc_nm_start (/var/bind/sbin/named+0x91ea94)
#3 0x5cc8f5 in create_managers (/var/bind/sbin/named+0xe78f5)
#4 0x5cd5ea in setup (/var/bind/sbin/named+0xe85ea)
#5 0x5cdc89 in main (/var/bind/sbin/named+0xe8c89)
#6 0xb71d9b40 in __libc_start_main ../csu/libc-start.c:308
SUMMARY: AddressSanitizer: heap-buffer-overflow (/var/bind/sbin/named+0x868e47) in der_get_oid
Shadow bytes around the buggy address:
0x369445d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x369445e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x369445f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36944600: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36944610: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x36944620: fa fa fa fa fa fa fa fa fa fa[04]fa fa fa 00 fa
0x36944630: fa fa 00 01 fa fa 00 04 fa fa 04 fa fa fa fd fa
0x36944640: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
0x36944650: fa fa fd fa fa fa fd fd fa fa fd fd fa fa fd fa
0x36944660: fa fa fd fa fa fa fd fd fa fa fd fa fa fa fd fd
0x36944670: fa fa fd fd fa fa fd fa fa fa fd fa fa fa fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==6064==ABORTINGCREDIT
This vulnerability was discovered by: Anonymous working with Trend Micro Zero Day Initiative
FURTHER DETAILS
If supporting files were contained with this report they are provided within a password protected ZIP file. The password is the ZDI candidate number in the form: ZDI-CAN-XXXX where XXXX is the ID number.
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ATTACHMENTS
[redacted]