Title: Orbit Downloader "Download failed" buffer overflow
Advisory ID: CORE-2008-0314
Advisory URL: https://www.coresecurity.com/core-labs/advisories/orbit-downloader
Date published: 2008-04-03
Date of last update: 2008-04-03
Vendors contacted: Orbit Downloader team
Release mode: Coordinated release
Orbit downloader  is vulnerable to a buffer overflow attack, which can be exploited by malicious remote attackers to execute arbitrary code. The vulnerability is due to Orbit not properly converting an URL ascii string to unicode. This can be exploited to execute arbitrary code by downloading a file from a specially crafted URL.
- Orbit downloader 2.6.3 and 2.6.4.
- Older versions could be vulnerables too, but they were not tested.
- Orbit downloader 2.6.5.
Vendor Information, Solutions and Workarounds
Update to Orbit downloader 2.6.5, available at http://dl.orbitdownloader.com/dl/OrbitDownloaderSetup.exe, or visit the vendor homepage at http://www.orbitdownloader.com.
This vulnerability was discovered and researched by Diego Juarez from Core Security Technologies.
Technical Description / Proof of Concept Code
When Orbit is unable to download a file, a balloon control is popped in the notification area. This is the code that takes care of drawing text to said control:
.text:004A56D0 sub_4A56D0 proc near ; CODE XREF: sub_42AAC0+321 p .text:004A56D0 ; sub_439610+321 p ... .text:004A56D0 .text:004A56D0 String = word ptr -2000h .text:004A56D0 hDC = dword ptr 4 .text:004A56D0 arg_4 = dword ptr 8 .text:004A56D0 lpRect = dword ptr 0Ch .text:004A56D0 uFormat = dword ptr 10h .text:004A56D0 .text:004A56D0 mov eax, 2000h ; reserve 0x2000 (8192) bytes in the stack .text:004A56D5 call __alloca_probe .text:004A56DA push edi .text:004A56DB mov ecx, 800h .text:004A56E0 xor eax, eax .text:004A56E2 lea edi, [esp+2004h+String] .text:004A56E6 rep stosd .text:004A56E8 mov eax, [esp+2004h+arg_4] .text:004A56EF pop edi .text:004A56F0 mov ecx, [eax+8] .text:004A56F3 mov eax, [eax+4] .text:004A56F6 test eax, eax .text:004A56F8 jnz short loc_4A56FF .text:004A56FA mov eax, ds:[email protected][email protected]? [email protected]? [email protected]@[email protected]@V? [email protected]@[email protected]@[email protected]@[email protected] ; .text:004A56FF .text:004A56FF loc_4A56FF: ; CODE XREF: sub_4A56D0+28 j .text:004A56FF lea edx, [esp+2000h+String] .text:004A5703 push 2000h ; cchWideChar (write up to 16384 bytes to the buffer) .text:004A5708 push edx ; lpWideCharStr .text:004A5709 push ecx ; cchMultiByte .text:004A570A push eax ; lpMultiByteStr .text:004A570B push 0 ; dwFlags .text:004A570D push 0 ; CodePage .text:004A570F call ds:MultiByteToWideChar .text:004A5715 mov ecx, [esp+2000h+uFormat] .text:004A571C mov edx, [esp+2000h+lpRect] .text:004A5723 push ecx ; uFormat .text:004A5724 mov ecx, [esp+2004h+hDC] .text:004A572B push edx ; lpRect .text:004A572C push eax ; nCount .text:004A572D lea eax, [esp+200Ch+String] .text:004A5731 push eax ; lpString .text:004A5732 push ecx ; hDC .text:004A5733 call ds:DrawTextW .text:004A5739 add esp, 2000h .text:004A573F retn .text:004A573F endp ;sub_4A56D0
According to MSDN , the Win32 API function
int MultiByteToWideChar( UINT CodePage, DWORD dwFlags, LPCSTR lpMultiByteStr, int cbMultiByte, LPWSTR lpWideCharStr, int cchWideChar );
has a parameter
cchWideChar which should be the "size, in WCHAR values, of the buffer indicated by lpWideCharStr". By supplying a download URL longer than 4096 bytes, if the download fails,
MultiByteToWideChar will overflow the 8192 bytes buffer in the stack and write up to 0x2000 WCHARs (16384 bytes) to it, overwriting internal structures and enabling arbitrary code execution.
- 2008-03-19: Core Security Technologies notifies the Orbit team of the vulnerability.
- 2008-03-27: The Orbit team asks Core Security Technologies for technical description of the vulnerability.
- 2008-03-27: Technical details sent to Orbit team by Core Security Technologies.
- 2008-04-03: Orbit notifies Core Security Technologies that a fix has been produced.
- 2008-04-03: CORE-2008-0314 advisory is published.
CoreLabs, the research center of Core Security, A HelpSystems Company is charged with researching and understanding security trends as well as anticipating the future requirements of information security technologies. CoreLabs studies cybersecurity trends, focusing on problem formalization, identification of vulnerabilities, novel solutions, and prototypes for new technologies. The team is comprised of seasoned researchers who regularly discover and discloses vulnerabilities, informing product owners in order to ensure a fix can be released efficiently, and that customers are informed as soon as possible. CoreLabs regularly publishes security advisories, technical papers, project information, and shared software tools for public use at https://www.coresecurity.com/core-labs.
About Core Security, A HelpSystems Company
Core Security, a HelpSystems Company, provides organizations with critical, actionable insight about who, how, and what is vulnerable in their IT environment. With our layered security approach and robust threat-aware, identity & access, network security, and vulnerability management solutions, security teams can efficiently manage security risks across the enterprise. Learn more at www.coresecurity.com.
The contents of this advisory are copyright (c) 2008 Core Security Technologies and (c) 2008 CoreLabs, and may be distributed freely provided that no fee is charged for this distribution and proper credit is given.
This advisory has been signed with the GPG key of Core Security advisories team.