Core Security - Corelabs Advisory http://corelabs.coresecurity.com/ EPS Viewer Buffer Overflow Vulnerability 1. *Advisory Information* Title: EPS Viewer Buffer Overflow Vulnerability Advisory ID: CORE-2013-0808 Advisory URL: http://www.coresecurity.com/advisories/eps-viewer-buffer-overflow-vulnerability Date published: 2013-08-28 Date of last update: 2013-08-28 Vendors contacted: EPS Viewer Team Release mode: User release 2. *Vulnerability Information* Class: Buffer overflow [CWE-119] Impact: Code execution Remotely Exploitable: Yes Locally Exploitable: No CVE Name: CVE-2013-4979 3. *Vulnerability Description* EPS Viewer [1], [2] is prone to a security vulnerability when processing EPS files. This vulnerability could be exploited by a remote attacker to execute arbitrary code on the target machine by enticing EPS Viewer users to open a specially crafted EPS file (client-side vulnerability). 4. *Vulnerable Packages* . EPS viewer v3.2. . Older versions are probably affected too, but they were not checked. 5. *Vendor Information, Solutions and Workarounds* There was no official answer from EPS team after several attempts to report this vulnerability (see [Sec. 8]). As mitigation action, given that this is a client-side vulnerability, avoid to open untrusted EPS files. Contact vendor for further information. 6. *Credits* This vulnerability was discovered and researched by Daniel Kazimirow from Core Exploit Writers Team. The publication of this advisory was coordinated by Fernando Miranda from Core Advisories Team. 7. *Technical Description / Proof of Concept Code* Below is shown the result of opening the maliciously crafted EPS file [3], which means the normal execution flow can be altered in order to execute arbitrary code. /----- 10089B0E . 8BFF MOV EDI,EDI 10089B10 > 8B46 08 MOV EAX,DWORD PTR DS:[ESI+8] ; <--- crash (we control ESI) 10089B13 . 8B48 0C MOV ECX,DWORD PTR DS:[EAX+C] 10089B16 . 830E FE OR DWORD PTR DS:[ESI],FFFFFFFE 10089B19 . 85C9 TEST ECX,ECX 10089B1B . 8B7E 04 MOV EDI,DWORD PTR DS:[ESI+4] 10089B1E . 74 0C JE SHORT gsdll32.10089B2C 10089B20 . 50 PUSH EAX 10089B21 . 57 PUSH EDI 10089B22 . 8D56 10 LEA EDX,DWORD PTR DS:[ESI+10] 10089B25 . 52 PUSH EDX 10089B26 . 53 PUSH EBX 10089B27 . FFD1 CALL ECX ; jump to our code -----/ The vulnerability exists in gldll32.dll module: /----- Executable modules, item 1 Base=10000000 Size=00A93000 (11087872.) Entry=102162B0 gsdll32.<ModuleEntryPoint> Name=gsdll32 Path=C:\Program Files\EPSViewer\gsdll32.dll EAX 035126E0 ASCII "TTEEEETTTTTTTTTTUVWXYZXYTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU ECX 00000000 EDX 00000028 EBX 0358A058 ESP 0012DA98 EBP 54545454 ESI 54544545 EDI 00000038 EIP 10089B10 gsdll32.10089B10 C 1 ES 0023 32bit 0(FFFFFFFF) P 0 CS 001B 32bit 0(FFFFFFFF) A 0 SS 0023 32bit 0(FFFFFFFF) Z 0 DS 0023 32bit 0(FFFFFFFF) S 1 FS 003B 32bit 7FFDE000(FFF) T 0 GS 0000 NULL D 0 O 0 LastErr ERROR_SUCCESS (00000000) EFL 00000283 (NO,B,NE,BE,S,PO,L,LE) ST0 empty 0.0 ST1 empty 2.5453186035156250000 ST2 empty 2.1025514602661132810 ST3 empty 320326.00000000000000 ST4 empty -312.81835937500000000 ST5 empty 0.0 ST6 empty 0.2500000000000000000 ST7 empty 250.96191406250000000 3 2 1 0 E S P U O Z D I FST 0120 Cond 0 0 0 1 Err 0 0 1 0 0 0 0 0 (LT) FCW 027F Prec NEAR,53 Mask 1 1 1 1 1 1 -----/ 8. *Report Timeline* . 2013-08-12: Core attempts to contact the EPS Viewer team, no reply received. Publication date is set for Aug 27th, 2013. . 2013-08-20: Core attempts to contact vendor. . 2013-08-26: Core attempts to contact vendor. . 2013-08-27: Release date missed. . 2013-08-28: After 3 attempts to contact vendor, the advisory CORE-2013-0808 is published as 'user release'. 9. *References* [1] http://epsviewer.org/. [2] http://epsviewer.org/download.aspx. [3] http://www.coresecurity.com/system/files/attachments/2013/08/CORE-2013-0808-epsviewer-poc-8321106075.zip 10. *About CoreLabs* CoreLabs, the research center of Core Security Technologies, is charged with anticipating the future needs and requirements for information security technologies. We conduct our research in several important areas of computer security including system vulnerabilities, cyber attack planning and simulation, source code auditing, and cryptography. Our results include problem formalization, identification of vulnerabilities, novel solutions and prototypes for new technologies. CoreLabs regularly publishes security advisories, technical papers, project information and shared software tools for public use at: http://corelabs.coresecurity.com. 11. *About Core Security Technologies* Core Security Technologies enables organizations to get ahead of threats with security test and measurement solutions that continuously identify and demonstrate real-world exposures to their most critical assets. Our customers can gain real visibility into their security standing, real validation of their security controls, and real metrics to more effectively secure their organizations. Core Security's software solutions build on over a decade of trusted research and leading-edge threat expertise from the company's Security Consulting Services, CoreLabs and Engineering groups. Core Security Technologies can be reached at +1 (617) 399-6980 or on the Web at: http://www.coresecurity.com. 12. *Disclaimer* The contents of this advisory are copyright (c) 2013 Core Security Technologies and (c) 2013 CoreLabs, and are licensed under a Creative Commons Attribution Non-Commercial Share-Alike 3.0 (United States) License: http://creativecommons.org/licenses/by-nc-sa/3.0/us/ 13. *PGP/GPG Keys* This advisory has been signed with the GPG key of Core Security Technologies advisories team, which is available for download at http://www.coresecurity.com/files/attachments/core_security_advisories.asc.