PJSIP syntax error exception when parsing 'Request Line'

When we were on chan_sip we someone was forcing chan_sip to call international numbers without registering. I noticed this error in our logs since switching to PJSIP and I think it is one of the hack attempts. The odd number being dialed looks like some previous attempts. I seen a 011 before too.

[2018-08-28 16:01:42] ERROR[15749]: pjproject:0 <?>: sip_transport.c Error processing 1334 bytes packet from UDP 37.49.231.122:8617 : PJSIP syntax error exception when parsing ‘Request Line’ header on line 1 col 76:
INVITE sip:800848221634223@49.197.19.1:5060;transport=udp;user=100’or’3=3-- SIP/2.0
Via: SIP/2.0/UDP 37.49.231.122:8617;branch=z9hG4bK-650228-1—czdyyrt4189t1umb;rport
Max-Forwards: 70
Contact: sip:100’or’3=3--@37.49.231.122:8617;transport=udp
To: sip:800848221634223@49.197.19.1:5060;transport=udp
From: sip:100’or’3=3--@37.49.231.122:8617;transport=udp;user=100’or’3=3--;tag=ssbnils1v85b
Call-ID: KcvMSQb9BKZ08NICP5ON5S…
CSeq: 1 INVITE
Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, MESSAGE, OPTIONS, INFO, SUBSCRIBE
Content-Type: application/sdp
User-Agent: Skipper IPhone
Allow-Events: presence, kpml, talk
Content-Length: 671

v=0
o=100’or’3=3-- 0 0 IN IP4 37.49.231.122
s=100’or’3=3–
c=IN IP4 37.49.231.122
t=0 0
m=audio 8000 RTP/AVP 106 9 18 3 111 0 8 97 110 112 98 101 100 99 102
a=rtpmap:106 opus/48000/2
a=fmtp:106 minptime=20; cbr=1; maxaveragebitrate=40000; useinbandfec=1
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:111 speex/16000
a=rtpmap:97 iLBC/8000
a=fmtp:97 mode=20
a=rtpmap:110 speex/8000
a=rtpmap:112 speex/32000
a=rtpmap:98 telephone-event/48000
a=fmtp:98 0-16
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=rtpmap:100 telephone-event/16000
a=fmtp:100 0-16
a=rtpmap:99 telephone-event/32000
a=fmtp:99 0-16
a=rtpmap:102 G726-32/8000
a=sendrecv

– end of packet.

This appears to be an attack attempting to leverage SQL injection. Since PJSIP parses and validates SIP traffic almost immediately after reading from the network it drops it early.

2 Likes

We are seeing a lot of Syntax errors too but not from hacking. Logs have a bunch like these. We’ve recently moved to PJSIP 13.22.0. I’m not seeing were there is a syntax problem.

[2018-10-12 20:33:58] ERROR[754] pjproject: sip_transport.c Error processing 423 bytes packet from TCP 10.5.30.102:29991 : PJSIP syntax error exception when parsing ‘Request Line’ header on line 1 col 58:
ACK sip:7137976703@tay03.teleflexnet.net:5060;user=phone SIP/2.0
Via: SIP/2.0/TCP 10.5.30.102:5060;branch=z9hG4bK412599626sansay1644267153rdb70687
To: sip:7137976703@tay03.teleflexnet.net:5060;user=phone;tag=z9hG4bK412599626sansay1644267153rdb70687
From: “Charles<121>” sip:100756121@tay03.teleflexnet.net:5060;tag=c21a7d2199
Call-ID: a783446d5e50d8fd
CSeq: 412599626 ACK
Max-Forwards: 70
Content-Length: 0