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Cisco AnyConnect Secure Mobility Client Remote Command Execution

High

Advisory ID

ZSL-2015-5246

Release Date

13 June 2015

Vendor

Cisco Systems, Inc. - http://www.cisco.com

Affected Version

2.x, 3.0, 3.0.0A90, 3.1.0472, 3.1.05187, 3.1.06073, 3.1.06078, 3.1.06079, 3.1.07021, 3.1.08009, 4.0.00013, 4.0.00048, 4.0.00051, 4.0.02052, 4.0.00057, 4.0.00061, 4.1.00028

CVE

N/A

Tested On

Microsoft Windows 7 Professional SP1 (EN) 32/64bit, Microsoft Windows 7 Ultimate SP1 (EN) 32/64bit

Summary

Cisco AnyConnect Secure Mobility Solution empowers your employees to work from anywhere, on corporate laptops as well as personal mobile devices, regardless of physical location. It provides the security necessary to help keep your organization’s data safe and protected.

Description

The AnyConnect Secure Mobility Client VPN API suffers from a stack buffer overflow vulnerability when parsing large amount of bytes to the 'strHostNameOrAddress' parameter in 'ConnectVpn' function which resides in the vpnapi.dll library, resulting in memory corruption and overflow of the stack. An attacker can gain access to the system of the affected node and execute arbitrary code.

(f48.10cc): Unknown exception - code 000006ba (first chance)
(f48.10cc): C++ EH exception - code e06d7363 (first chance)
(f48.10cc): C++ EH exception - code e06d7363 (first chance)
(f48.10cc): Stack overflow - code c00000fd (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for C:\Program Files (x86)\Cisco\Cisco AnyConnect Secure Mobility Client\vpnapi.dll -
eax=00232000 ebx=02df9128 ecx=00000000 edx=088f0024 esi=01779c42 edi=088f0022
eip=748b6227 esp=0032ea14 ebp=0032eab0 iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00210206
vpnapi!ConnectIfcData::setConfigCookie+0x9195:
748b6227 8500            test    dword ptr [eax],eax  ds:002b:00232000=00000000
0:000> g
(f48.10cc): Stack overflow - code c00000fd (!!! second chance !!!)
eax=00232000 ebx=02df9128 ecx=00000000 edx=088f0024 esi=01779c42 edi=088f0022
eip=748b6227 esp=0032ea14 ebp=0032eab0 iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00210206
vpnapi!ConnectIfcData::setConfigCookie+0x9195:
748b6227 8500            test    dword ptr [eax],eax  ds:002b:00232000=00000000
0:000> d edi
088f0022  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0032  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0042  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0052  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0062  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0072  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0082  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0092  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
0:000> d edx
088f0024  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0034  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0044  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0054  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0064  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0074  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0084  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.
088f0094  41 00 41 00 41 00 41 00-41 00 41 00 41 00 41 00  A.A.A.A.A.A.A.A.

<12308000 B

----

>512150-512154 B

First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for C:\Windows\syswow64\RPCRT4.dll -
eax=004d2384 ebx=76e9b7e4 ecx=00193214 edx=00000000 esi=00193214 edi=00193738
eip=75440fc4 esp=00193000 ebp=00193008 iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00210206
RPCRT4!UuidCreate+0x835:
75440fc4 56              push    esi
0:000> g
(1a50.1e40): Stack overflow - code c00000fd (!!! second chance !!!)
eax=004d2384 ebx=76e9b7e4 ecx=00193214 edx=00000000 esi=00193214 edi=00193738
eip=75440fc4 esp=00193000 ebp=00193008 iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00210206
RPCRT4!UuidCreate+0x835:
75440fc4 56              push    esi
0:000> d eax
004d2384  46 75 6e 63 74 69 6f 6e-3a 20 43 6c 69 65 6e 74  Function: Client
004d2394  49 66 63 42 61 73 65 3a-3a 67 65 74 43 6f 6e 6e  IfcBase::getConn
004d23a4  65 63 74 4d 67 72 0a 46-69 6c 65 3a 20 2e 5c 43  ectMgr.File: .\C
004d23b4  6c 69 65 6e 74 49 66 63-42 61 73 65 2e 63 70 70  lientIfcBase.cpp
004d23c4  0a 4c 69 6e 65 3a 20 32-35 38 30 0a 43 61 6c 6c  .Line: 2580.Call
004d23d4  20 74 6f 20 67 65 74 43-6f 6e 6e 65 63 74 4d 67   to getConnectMg
004d23e4  72 20 77 68 65 6e 20 6e-6f 74 20 63 6f 6e 6e 65  r when not conne
004d23f4  63 74 65 64 20 74 6f 20-41 67 65 6e 74 2e 00 00  cted to Agent...
0:000> d
004d2404  00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00  ................
004d2414  00 00 00 00 41 41 41 41-41 41 41 41 41 41 41 41  ....AAAAAAAAAAAA
004d2424  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
004d2434  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
004d2444  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
004d2454  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
004d2464  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
004d2474  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
0:000> d esp+1500
00194500  00 00 00 00 f8 e6 28 00-ec 3c 85 74 04 00 00 00  ......(..<.t....
00194510  ff ff ff ff 00 00 00 00-00 00 00 00 00 00 00 00  ................
00194520  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
00194530  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
00194540  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
00194550  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
00194560  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA
00194570  41 41 41 41 41 41 41 41-41 41 41 41 41 41 41 41  AAAAAAAAAAAAAAAA

Proof of Concept

anyconnect_bof.htmlTXT

Disclosure Timeline

25.03.2015Vulnerability discovered.

28.03.2015Vendor contacted.

29.03.2015Vendor responds asking more details.

13.04.2015Sent details to the vendor.

15.04.2015Asked vendor for status update.

15.04.2015Vendor opens case #PSIRT-0089839229, informing that as soon as incident manager takes ownership of the case they will be in contact.

22.04.2015Asked vendor for status update.

28.04.2015No reply from the vendor.

04.05.2015Asked vendor for status update.